AIM: To determine characteristics and prognosticpredictors of patients with hepatocellular carcinoma(HCC) in association with non-alcoholic fatty liver disease(NAFLD).METHODS: We reviewed the records of all patients w...AIM: To determine characteristics and prognosticpredictors of patients with hepatocellular carcinoma(HCC) in association with non-alcoholic fatty liver disease(NAFLD).METHODS: We reviewed the records of all patients with NAFLD associated HCC between 2000 and 2012. Data collected included demographics; histology; presence or absence of cirrhosis, size and number of HCC, alpha-fetoprotein, body mass index(BMI), and the presence of diabetes, hypertension, or dyslipidaemia.RESULTS: Fifty-four patients with NAFLD associated HCC were identified. Mean age was 64 years with 87% male. Fifteen percent(8/54) were not cirrhotic. 11%, 24% and 50% had a BMI of < 25 kg/m2, 25-29 kg/m2 and ≥ 30 kg/m2 respectively. Fifty-nine percent were diabetic, 44% hypertensive and 26% hyperlipidaemic. Thirty-four percent of the patients had ≤ 1 of these risk factors. Non-cirrhotics had a significantly larger mean tumour diameter at diagnosis than cirrhotics(P = 0.041). Multivariate analysis did not identify any other patient characteristics that predicted the size or number of HCC.CONCLUSION: HCC can develop in NAFLD without cirrhosis. At diagnosis such tumours are larger than those in cirrhotics, conferring a poorer prognosis.展开更多
Designing the optimal distribution of Global Navigation Satellite System(GNSS)ground stations is crucial for determining the satellite orbit,satellite clock and Earth Rotation Parameters(ERP)at a desired precision usi...Designing the optimal distribution of Global Navigation Satellite System(GNSS)ground stations is crucial for determining the satellite orbit,satellite clock and Earth Rotation Parameters(ERP)at a desired precision using a limited number of stations.In this work,a new criterion for the optimal GNSS station distribution for orbit and ERP determination is proposed,named the minimum Orbit and ERP Dilution of Precision Factor(OEDOP)criterion.To quickly identify the specific station locations for the optimal station distribution on a map,a method for the rapid determination of the selected station locations is developed,which is based on the map grid zooming and heuristic technique.Using the minimum OEDOP criterion and the proposed method for the rapid determination of optimal station locations,an optimal or near-optimal station distribution scheme for 17 newly built BeiDou Navigation Satellite System(BDS)global tracking stations is suggested.To verify the proposed criterion and method,real GNSS data are processed.The results show that the minimum OEDOP criterion is valid,as the smaller the value of OEDOP,the better the precision of the satellite orbit and ERP determination.Relative to the exhaustive method,the proposed method significantly improves the computational efficiency of the optimal station location determination.In the case of 3 newly built stations,the computational efficiency of the proposed method is 35 times greater than that of the exhaustive method.As the number of stations increases,the improvement in the computational efficiency becomes increasingly obvious.展开更多
Based on the structural characteristics of the double-differenced normal equation, a new method was proposed to resolve the ambiguity float solution through a selection of parameter weights to construct an appropriate...Based on the structural characteristics of the double-differenced normal equation, a new method was proposed to resolve the ambiguity float solution through a selection of parameter weights to construct an appropriate regularized matrix, and a singular decomposition method was used to generate regularization parameters. Numerical test results suggest that the regularized ambiguity float solution is more stable and reliable than the least-squares float solution. The mean square error matrix of the new method possesses a lower correlation than the variancecovariance matrix of the least-squares estimation. The size of the ambiguity search space is reduced and the search efficiency is improved. The success rate of the integer ambiguity searching process is improved significantly when the ambiguity resolution by using constraint equation method is used to determine the correct ambiguity integervector. The ambiguity resolution by using constraint equation method requires an initial input of the ambiguity float solution candidates which are obtained from the LAMBDA method in the new method. In addition, the observation time required to fix reliable integer ambiguities can he significantly reduced.展开更多
More effective environmental pollution control and management are needed due to the increasing environ-mental impacts from a range of human activities and the growing public demands for a better living environment. Ur...More effective environmental pollution control and management are needed due to the increasing environ-mental impacts from a range of human activities and the growing public demands for a better living environment. Urban air pollution is a serious environmental issue that poses adverse impacts on the health of people and the environment in most metropolitan areas. In this paper,we propose a geoinformatics augmented framework of environmental modelling and information sharing for supporting effective urban air pollution control and management. This framework is out-lined in terms of its key components and processes including: 1) an integrated,adaptive network of sensors for envi-ronmental monitoring; 2) a set of distributed,interoperable databases for data management; 3) a set of intelligent,robust algorithms and models for environmental modelling; 4) a set of flexible,efficient user interfaces for data access and in-formation sharing; and 5) a reliable,high capacity,high performance computing and communication infrastructure for integrating and supporting other framework components and processes.展开更多
Background: Canopy structure, defined by leaf area index (LAI), fractional vegetation cover (FCover) and fraction of absorbed photosynthetically active radiation (fAPAR), regulates a wide range of forest functi...Background: Canopy structure, defined by leaf area index (LAI), fractional vegetation cover (FCover) and fraction of absorbed photosynthetically active radiation (fAPAR), regulates a wide range of forest functions and ecosystem services. Spatially consistent field-measurements of canopy structure are however lacking, particularly for the tropics. Methods: Here, we introduce the Global LAI database: a global dataset of field-based canopy structure measurements spanning tropical forests in four continents (Africa, Asia, Australia and the Americas). We use these measurements to test for climate dependencies within and across continents, and to test for the potential of anthropogenic disturbance and forest protection to modulate those dependences. Results: Using data collected from 887 tropical forest plots, we show that maximum water deficit, defined across the most arid months of the year, is an important predictor of canopy structure, with all three canopy attributes declining significantly with increasing water deficit. Canopy attributes also increase with minimum temperature, and with the protection of forests according to both active (within protected areas) and passive measures (through topography). Once protection and continent effects are accounted for, other anthropogenic measures (e.g. human population) do not improve the model. Conclusions: We conclude that canopy structure in the tropics is primarily a consequence of forest adaptation to the maximum water deficits historically experienced within a given region. Climate change, and in particular changes in drought regimes may thus affect forest structure and function, but forest protection may offer some resilience against this effect.展开更多
In this secondary research, published works on effect of climate change on water resources in other countries and in Australia were reviewed critically. Research question, objectives and assumptions were made to facil...In this secondary research, published works on effect of climate change on water resources in other countries and in Australia were reviewed critically. Research question, objectives and assumptions were made to facilitate this study. First, methods used for such studies and their results at global level were reviewed. Then Australian specific methods of study and findings were reviewed. More commonly, both globally and in Australia, simulations using long-term real data on selected climatic scenarios of global climatic models are projected for long-term future trends. The validity and certainty of predicted occurrences depend upon the closeness of real time data with scenarios to which they are projected. Even with these limitations, projections of already rising temperatures and declining rainfall on surface water and ground water availabilities show gradual decline in water availability leading to water stress both for human communities and ecosystems The role of human-induced emissions in hastening the degradation process has also been investigated. Conserving all available water, practising efficient water consumption and prudent water policies only can provide some relief from what is inevitable.展开更多
Increases in the frequency of extreme weather and climate events and the severity of their impacts on the natural environment and society have been observed across the globe in recent decades. In addition to natural c...Increases in the frequency of extreme weather and climate events and the severity of their impacts on the natural environment and society have been observed across the globe in recent decades. In addition to natural climate variability and greenhouse-induced climate change, extreme weather and climate events produce the most pronounced impacts. In this paper, the climate of three island countries in the Western Pacific: Fiji, Samoa and Tuvalu, has been analysed. Warming trends in annual average maximum and minimum temperatures since the 1950s have been identified, in line with the global warming trend. We present recent examples of extreme weather and climate events and their impacts on the island countries in the Western Pacific: the 2011 drought in Tuvalu, the 2012 floods in Fiji and a tropical cyclone, Evan, which devastated Samoa and Fiji in December 2012. We also relate occurrences of the extreme weather and climate events to phases of the El Niño-Southern Oscillation (ENSO) phenomenon. The impacts of such natural disasters on the countries are severe and the costs of damage are astronomical. In some cases, climate extremes affect countries to such an extent that governments declare a national state of emergency, as occurred in Tuvalu in 2011 due to the severe drought’s impact on water resources. The projected increase in the frequency of weather and climate extremes is one of the expected consequences of the observed increase in anthropogenic greenhouse gas concentration and will likely have even stronger negative impacts on the natural environment and society in the future. This should be taken into consideration by authorities of Pacific Island Countries and aid donors when developing strategies to adapt to the increasing risk of climate extremes. Here we demonstrate that the modern science of seasonal climate prediction is well developed, with current dynamical climate models being able to provide skilful predictions of regional rainfall two-three months in advance. The dynamic climate model-based forecast products are now disseminated to the National Meteorological Services of 15 island countries in the Western Pacific through a range of web-based information tools. We conclude with confidence that seasonal climate prediction is an effective solution at the regional level to provide governments and local communities of island nations in the Western Pacific with valuable assistance for informed decision making for adaptation to climate variability and change.展开更多
This paper points out that delayed or no supply of software can kill potential benefits associated with new mathematical ideas that have led to development of new mathematics in OR. It also points out that it is a sel...This paper points out that delayed or no supply of software can kill potential benefits associated with new mathematical ideas that have led to development of new mathematics in OR. It also points out that it is a self-created situation by the scientific community. This situation needs attention and should be resolved urgently. Many illustrative examples have been given to justify the claim</span></span><span>.展开更多
A recent trend of sea level shows constant rising. Sea level rise has caused a significant risk to seaside areas. This study examines the potential effect of climate change and rising sea levels on coastal regions and...A recent trend of sea level shows constant rising. Sea level rise has caused a significant risk to seaside areas. This study examines the potential effect of climate change and rising sea levels on coastal regions and evaluates the susceptibility of coastal areas in Inverloch, Melbourne Australia. A model of Hypothetically Flooded Zones, based on LiDAR data was built, processed and manipulated in ArcGIS. Through applying this model, the effect of rising sea level on the infrastructures such as buildings, dwellings, roads, land use and the population was assessed. Elevation data sets of varying resolution and accuracy have been processed to show the improved quality of LiDAR data contributes to a more precise delineation of flood-prone coastal lands. After the susceptible areas to sea level rise were delineated, the worst-case scenario was calculated (based on the increase in sea level projected for 2100) and it would impacts about 0.86% of roads, 221 of different building infrastructures. This method can be used in other areas to protect the coasts due to rapid changes caused by climate change.展开更多
In recent years, radio occultation (RO) technology making use of global positioning system (GPS) signals has been exploited to obtain profiles of atmospheric parameters in the neutral atmosphere. In this paper, th...In recent years, radio occultation (RO) technology making use of global positioning system (GPS) signals has been exploited to obtain profiles of atmospheric parameters in the neutral atmosphere. In this paper, the RO refractivity profiles obtained from the Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC) mission are statistically compared with the observations of 38 radiosonde stations provided by the Australian Bureau of Meteorology during the period from 15 July 2006 through 15 July 2007. Different collocation criteria are compared at first, and COSMIC RO soundings that occur within 3 hours and 300 km of radiosonde measurements are used for the final statistical comparison. The overall results show that the agreements between the COSMIC refractivity profiles and the radiosonde soundings from the 38 stations are very good at 0-30 km altitude, with mean absolute relative refractivity deviations of less than 0.5%. Latitudinal comparisons indicate that there are negative refractivity deviations in the lower troposphere over the low latitude and middle latitude regions and large standard deviations exist in the lower troposphere of low latitude regions, which can reach up to ~6%. The comparisons of COSMIC RO refractivity profiles and radiosonde observations for 3 polar stations in four different seasons indicate that the accuracy of GPS RO profiles is better in the Austral summer and autumn than in the Austral spring and winter during the year from September 2006 to August 2007.展开更多
Interferometric phase filtering is one of the key steps in interferometricsynthetic aperture radar (InSAR/SAR). However, the ideal filtering results are difficult toobtain due to dense fringe and low coherence regions...Interferometric phase filtering is one of the key steps in interferometricsynthetic aperture radar (InSAR/SAR). However, the ideal filtering results are difficult toobtain due to dense fringe and low coherence regions. Moreover, the InSAR/SAR datarange is relatively large, so the efficiency of interferential phase filtering is one of themajor problems. In this letter, we proposed an interferometric phase filtering methodbased on an amended matrix pencil and linear window mean filter. The combination ofthe matrix pencil and the linear mean filter are introduced to the interferometric phasefiltering for the first time. First, the interferometric signal is analyzed, and theinterferometric phase filtering is transformed into a local frequency estimation problem.Then, the local frequency is estimated using an amended matrix pencil at a window. Thelocal frequency can represent terrain changes, thus suggesting that the frequency can beaccurately estimated even in dense fringe regions. Finally, the local frequency is filteredby using a linear window mean filter, and the filtered phase is recovered. The proposedmethod is calculated by some matrices. Therefore, the computational complexity isreduced, and the efficiency of the interferometric phase filtering is improved.Experiments are conducted with simulated and real InSAR data. The proposed methodexhibits a better filtering effect and an ideal efficiency as compared with the traditionalfiltering method.展开更多
CWD (coarse woody debris) plays an important role in nutrient cycling, habitat for species and more recently carbon accounting in forest ecosystems. LiDAR (light detection and ranging) technology has demonstrated ...CWD (coarse woody debris) plays an important role in nutrient cycling, habitat for species and more recently carbon accounting in forest ecosystems. LiDAR (light detection and ranging) technology has demonstrated utility in capturing forest structure information. This paper proposes an indirect method of assessing downed CWD using LiDAR derived forest structure variables. Fieldwork was conducted to measure CWD volume in an Eucalyptus forest in Tasmania. A GLM (generalized linear model) to statistically estimate CWD volume in the Eucalyptus forest was developed using a LiDAR derived FCS (forest characterisation scheme): the openings above the ground, low and medium vegetation, canopy cover, presence of understorey and mid-storey vegetation and high trees, and the vertical canopy density of high trees. Five structural variables were selected for the best model based on AIC (Akaike's Information Criterion) by stepwise selection. The applicability of the model was then compared to the outcome of model using field derived variables such as diameter at breast height of trees. The results show that the model using LiDAR derived variables better estimated the amount of CWD. It is concluded that LiDAR derived forest structural variables has the potential to predict the amount of downed CWD in Eucalyptus forest.展开更多
Climate change can impact coastal areas in different ways,including flooding,storm surges,and beach erosion.Of these,flooding has a major impact on the operation of coastal drainage systems.This paper develops a new f...Climate change can impact coastal areas in different ways,including flooding,storm surges,and beach erosion.Of these,flooding has a major impact on the operation of coastal drainage systems.This paper develops a new flood screening model using a LiDAR based digital elevation model(DEM)to improve the implementation of Victorian’s coastal flooding risk assessment and management.Hydrological elevation models are directed towards protection from cloudbursts and applied to rising sea level.The aim is to simulate water flow on the ground and in streams,and the resulting accumulation of water in depressions of the blue spot using DEM.Due to the presence of pipes,watercourses,bridges and channels it was required that the DEM data to be lowered.The reservoirs of rain will prevent seawater from flowing across the stream channel into land.The rain drain will be open during normal sea levels to allow rain water in the river to move and flow in to the sea.Traditionally,geographic information system(GIS)assists with spatial data management,but lacks modelling capability for complex hydrology problems and cannot be relied upon by decision-makers in this sector.Functionality improvements are therefore required to improve the processing or analytical capabilities of GIS in hydrology.This research shows how the spatial data can be primarily processed by GIS adopting the spatial analysis routines associated with hydrology.The objective of this paper is to outline the importance of GIS technology for coastal flood management.Following a definition of the coastal flood,and,short description of its peculiarities and the urgency of its management,this paper describes the use of GIS technology in coastal flood management,its advantages and the consideration for accuracy.This is followed by the information and LiDAR data required for coastal flood management and the application area in coastal flood management.This paper method is presented to conduct a first high-resolution DEM screening to detect the degree and capacities of the sinks in the coastal landscape.When their capacities are established,the rain volumes received during a rainstorm from their coastal catchments are saved as attributes to the pour points.The conclusion emphases the importance of a geographical information system in coastal flood management for efficient data handling and analysis of geographically related data.Local governments at risk of coastal flooding that use the flood screening model can use to determine appropriate land use controls to manage long-term flood risk to human settlements.展开更多
Water is a basic normal asset for supporting the condition of life. Accessible water assets are feeling the squeeze because of expanding demand. Soon water, which we have depended upon to be accessible and an uncondit...Water is a basic normal asset for supporting the condition of life. Accessible water assets are feeling the squeeze because of expanding demand. Soon water, which we have depended upon to be accessible and an unconditional present of nature will turn into a rare product. Protection and conservation of water assets are desperately required. In many parts of Victoria, water supply to communities is limited. Rainwater harvesting systems can provide water at or near the point of demand. The systems can be owner and utility operated and managed. Rainwater collected using existing structures, i.e. rooftops, parking lots, playgrounds, parks, ponds, floodplains etc., has few negative environmental impacts compared to other technologies for water resources development. Rainwater is relatively clean and the quality is usually acceptable for many purposes with little or even no treatment. The physical and chemical properties of rainwater are usually superior to sources of groundwater that may have been subjected to contamination. The present study was intended to measure the rooftop rainwater harvesting potential using GIS techniques. The GIS examination utilized in this investigation was basically an efficient assessment of rooftop water collecting in the chose Wollert which is a suburb in Melbourne, Victoria. With the use of GIS it was conceivable to appraise the aggregate sum of water harvestable at the household level. It is very tedious work to assess the catchments available for rooftop rainwater harvesting. Here the roof surfaces are the catchments and GIS is employed to calculate the area of various types of roofs and their potential for planning for the area under study. As a result Eucalypt Estate Wollert has huge potential and can make above 179.11 litres water available per person per day throughout the year.展开更多
Understanding urban wetland ecosystem services structure allows managers to base restoration efforts on multiple user end-benefits.Ary Creek can provide the coupled function of improving water quality and mitigating f...Understanding urban wetland ecosystem services structure allows managers to base restoration efforts on multiple user end-benefits.Ary Creek can provide the coupled function of improving water quality and mitigating floods through delayed stormwater flow.It is fundamental to identify areas surrounded by water for the safety of individual should in case the water level raise beyond a reasonable doubt and might cause a flood.For many years,the Ary Creek catchment in Inverloch has been flooding and causing great problems for the inhabitants as well as the environment.The procedure is to develop models of the area around the catchment or watershed using Victorian Coastal LiDAR and other input data from the GIS(geographic information system).This study uses the real-time simulation in ArcSWAT—ArcGIS 10.3 and 3D in ArcScene 10.3,and the variables obtained from the soil and water assessment tool ArcSWAT such as the land use,soil and slope are the parameters measured to induce the flood.When certain portions of the Hydrologic response unit HRU,land use,soil or slope is changed due to temporal adjustment and climate change,then the model can predict zones of low,moderate and high flood risk.The 3D simulations appear to produce a visual model for decision-making,planning,management,and mitigation.The simulation helps in determining the extent of the flood by using animation.展开更多
The main objective of this study is to determine how speed errors of test vehicles depend on tire pressure. In order to achieve this, experiments were conducted to find out how tire pressure depends on driving speed a...The main objective of this study is to determine how speed errors of test vehicles depend on tire pressure. In order to achieve this, experiments were conducted to find out how tire pressure depends on driving speed and how distance measurements depend on tire pressure. It is demonstrated that hot tires might have their pressure increased by 6% at 110 km/h speed relative to nominal tire pressure. Subsequently, experiments conducted on a surveyed test track proved that hot tires might increase speed measurement errors by 0.03%, whereas under-inflated tires might cause several times higher speed errors, It is critical that test vehicles involved in speed measurements have nominal tire pressure when tires are cold. In such instances, the uncertainty of speed measurements component related to tire pressure is relatively low. This research allowed quantifying the tire pressure error component for a specific test vehicle, while the experimental approach might be used for any other vehicles.展开更多
The ultimate aim of using spatial datasets and spatial data modelling is focused on enabling a sustainable environment by bringing the public policies into practice. The consequence will be sustainable spatially aware...The ultimate aim of using spatial datasets and spatial data modelling is focused on enabling a sustainable environment by bringing the public policies into practice. The consequence will be sustainable spatially aware strategic planning for all levels of Australian government. Geographical Information Systems (GIS) are the platform that can serve this aim provided that model, current process and spatial datasets are fit for purpose. To bring public policy into practice a broad range of knowledge from different disciplines is needed. Most decision making processes are pressured in terms of time and driving forces and also the process is beyond the knowledge of individuals in the various disciplines. There is a need for immediate uptake models and tools which are relevant to the target subject that will facilitate this decision making process. This paper focuses on realizing the utility in spatial data and spatial data handling in order to help climate change adaptation programs at local government level. Web-based mapping tools can assist planners prepare for the changing climate conditions in Bass Coast Shire Council. The GIS team has gathered data from various climate research organizations to understand projections of what different climate scenarios might look like over the next 100-year period. From this website demo it is hoped that the user will understand how the tool works, background information on different GIS platforms, access to interactive mapping, online geospatial analysis tools, videos, open source resource, sea level tools, modelling, 3D visualization and direct download access to various planning and natural resource data sets relating to environment management. Some results from our elevation data analyses through these Web map visualization tools are provided.展开更多
Tropical cyclones (TCs) are the most destructive weather phenomena to impact on tropical regions, and reliable predicttion of TC seasonal activity is important for preparedness of coastal communities in the tropics. I...Tropical cyclones (TCs) are the most destructive weather phenomena to impact on tropical regions, and reliable predicttion of TC seasonal activity is important for preparedness of coastal communities in the tropics. In investigating prospects for improving the skill of TC seasonal prediction in the South Indian and South Pacific Oceans, including the Australian Region, we used linear regression to model the relationship between the annual number of cyclones and three indices (SOI, NI?O3.4 and 5VAR) describing the strength of the El Ni?o-Southern Oscillation (ENSO). The correlation between the number of Australian Region (90?E - 160?E) TCs and the indices was strong (3-month 5VAR ?0.65, NI?O3.4 ?0.62 and SOI +0.64), and a cross-validation assessment demonstrated that the models which used July-August-September indices and the temporal trend as the predictors performed well. The predicted number of TCs in the Australian Region for 2010/2011 and 2011/2012 seasons was 14 (11 recorded) and 12, respectively. We also found that the correlation between the numbers of TCs in the western South Indian region (30?E to 90?E) and the eastern South Pacific region (east of 170?E) and the indices was weak, and it is therefore not sensible to build linear regression forecast models for these regions. We conclude that for the Australian Region, the new statistical model provides prospects for improvement in forecasting skill compared to the statistical model currently employed at the National Climate Centre, Australian Bureau of Meteorology. The next step towards improving the skill of TC seasonal prediction in the various regions of the Southern Hemisphere will be undertaken through analysis of outputs from the dynamical climate model POAMA (Predictive Ocean-Atmosphere Model for Australia).展开更多
文摘AIM: To determine characteristics and prognosticpredictors of patients with hepatocellular carcinoma(HCC) in association with non-alcoholic fatty liver disease(NAFLD).METHODS: We reviewed the records of all patients with NAFLD associated HCC between 2000 and 2012. Data collected included demographics; histology; presence or absence of cirrhosis, size and number of HCC, alpha-fetoprotein, body mass index(BMI), and the presence of diabetes, hypertension, or dyslipidaemia.RESULTS: Fifty-four patients with NAFLD associated HCC were identified. Mean age was 64 years with 87% male. Fifteen percent(8/54) were not cirrhotic. 11%, 24% and 50% had a BMI of < 25 kg/m2, 25-29 kg/m2 and ≥ 30 kg/m2 respectively. Fifty-nine percent were diabetic, 44% hypertensive and 26% hyperlipidaemic. Thirty-four percent of the patients had ≤ 1 of these risk factors. Non-cirrhotics had a significantly larger mean tumour diameter at diagnosis than cirrhotics(P = 0.041). Multivariate analysis did not identify any other patient characteristics that predicted the size or number of HCC.CONCLUSION: HCC can develop in NAFLD without cirrhosis. At diagnosis such tumours are larger than those in cirrhotics, conferring a poorer prognosis.
基金This work was supported by“The National Natural Science Foundation of China(No.41404033)”“The National Science and Technology Basic Work of China(No.2015FY310200)”+1 种基金“The State Key Program of National Natural Science Foundation of China(No.41730109)”“The Jiangsu Dual Creative Teams Program Project Awarded in 2017”and thanks for the data from IGS and iGMAS。
文摘Designing the optimal distribution of Global Navigation Satellite System(GNSS)ground stations is crucial for determining the satellite orbit,satellite clock and Earth Rotation Parameters(ERP)at a desired precision using a limited number of stations.In this work,a new criterion for the optimal GNSS station distribution for orbit and ERP determination is proposed,named the minimum Orbit and ERP Dilution of Precision Factor(OEDOP)criterion.To quickly identify the specific station locations for the optimal station distribution on a map,a method for the rapid determination of the selected station locations is developed,which is based on the map grid zooming and heuristic technique.Using the minimum OEDOP criterion and the proposed method for the rapid determination of optimal station locations,an optimal or near-optimal station distribution scheme for 17 newly built BeiDou Navigation Satellite System(BDS)global tracking stations is suggested.To verify the proposed criterion and method,real GNSS data are processed.The results show that the minimum OEDOP criterion is valid,as the smaller the value of OEDOP,the better the precision of the satellite orbit and ERP determination.Relative to the exhaustive method,the proposed method significantly improves the computational efficiency of the optimal station location determination.In the case of 3 newly built stations,the computational efficiency of the proposed method is 35 times greater than that of the exhaustive method.As the number of stations increases,the improvement in the computational efficiency becomes increasingly obvious.
文摘Based on the structural characteristics of the double-differenced normal equation, a new method was proposed to resolve the ambiguity float solution through a selection of parameter weights to construct an appropriate regularized matrix, and a singular decomposition method was used to generate regularization parameters. Numerical test results suggest that the regularized ambiguity float solution is more stable and reliable than the least-squares float solution. The mean square error matrix of the new method possesses a lower correlation than the variancecovariance matrix of the least-squares estimation. The size of the ambiguity search space is reduced and the search efficiency is improved. The success rate of the integer ambiguity searching process is improved significantly when the ambiguity resolution by using constraint equation method is used to determine the correct ambiguity integervector. The ambiguity resolution by using constraint equation method requires an initial input of the ambiguity float solution candidates which are obtained from the LAMBDA method in the new method. In addition, the observation time required to fix reliable integer ambiguities can he significantly reduced.
文摘More effective environmental pollution control and management are needed due to the increasing environ-mental impacts from a range of human activities and the growing public demands for a better living environment. Urban air pollution is a serious environmental issue that poses adverse impacts on the health of people and the environment in most metropolitan areas. In this paper,we propose a geoinformatics augmented framework of environmental modelling and information sharing for supporting effective urban air pollution control and management. This framework is out-lined in terms of its key components and processes including: 1) an integrated,adaptive network of sensors for envi-ronmental monitoring; 2) a set of distributed,interoperable databases for data management; 3) a set of intelligent,robust algorithms and models for environmental modelling; 4) a set of flexible,efficient user interfaces for data access and in-formation sharing; and 5) a reliable,high capacity,high performance computing and communication infrastructure for integrating and supporting other framework components and processes.
基金supported by the‘Uncovering the variable roles of fire in savannah ecosystems’project,funded by Leverhulme Trust under grant IN-2014-022 and‘Resilience in East African Landscapes’project funded by European Commission Marie Curie Initial Training Network(FP7-PEOPLE-2013-ITN project number606879)funding from Australian Research Council,IUCN Sustain/African Wildlife Foundation and University of York Research Pump Priming Fund+1 种基金funding through the European Research Council ERC-2011-St G_20101109(project number 281986)and the British Ecological Society-Ecologists in Africa programmesupport through the‘Climate Change Impacts on Ecosystem Services and Food Security in Eastern Africa(CHIESA)’project(2011–2015),which was funded by the Ministry for Foreign Affairs of Finland,and coordinated by the International Centre of Insect Physiology and Ecology(icipe)in Nairobi,Kenya
文摘Background: Canopy structure, defined by leaf area index (LAI), fractional vegetation cover (FCover) and fraction of absorbed photosynthetically active radiation (fAPAR), regulates a wide range of forest functions and ecosystem services. Spatially consistent field-measurements of canopy structure are however lacking, particularly for the tropics. Methods: Here, we introduce the Global LAI database: a global dataset of field-based canopy structure measurements spanning tropical forests in four continents (Africa, Asia, Australia and the Americas). We use these measurements to test for climate dependencies within and across continents, and to test for the potential of anthropogenic disturbance and forest protection to modulate those dependences. Results: Using data collected from 887 tropical forest plots, we show that maximum water deficit, defined across the most arid months of the year, is an important predictor of canopy structure, with all three canopy attributes declining significantly with increasing water deficit. Canopy attributes also increase with minimum temperature, and with the protection of forests according to both active (within protected areas) and passive measures (through topography). Once protection and continent effects are accounted for, other anthropogenic measures (e.g. human population) do not improve the model. Conclusions: We conclude that canopy structure in the tropics is primarily a consequence of forest adaptation to the maximum water deficits historically experienced within a given region. Climate change, and in particular changes in drought regimes may thus affect forest structure and function, but forest protection may offer some resilience against this effect.
文摘In this secondary research, published works on effect of climate change on water resources in other countries and in Australia were reviewed critically. Research question, objectives and assumptions were made to facilitate this study. First, methods used for such studies and their results at global level were reviewed. Then Australian specific methods of study and findings were reviewed. More commonly, both globally and in Australia, simulations using long-term real data on selected climatic scenarios of global climatic models are projected for long-term future trends. The validity and certainty of predicted occurrences depend upon the closeness of real time data with scenarios to which they are projected. Even with these limitations, projections of already rising temperatures and declining rainfall on surface water and ground water availabilities show gradual decline in water availability leading to water stress both for human communities and ecosystems The role of human-induced emissions in hastening the degradation process has also been investigated. Conserving all available water, practising efficient water consumption and prudent water policies only can provide some relief from what is inevitable.
文摘Increases in the frequency of extreme weather and climate events and the severity of their impacts on the natural environment and society have been observed across the globe in recent decades. In addition to natural climate variability and greenhouse-induced climate change, extreme weather and climate events produce the most pronounced impacts. In this paper, the climate of three island countries in the Western Pacific: Fiji, Samoa and Tuvalu, has been analysed. Warming trends in annual average maximum and minimum temperatures since the 1950s have been identified, in line with the global warming trend. We present recent examples of extreme weather and climate events and their impacts on the island countries in the Western Pacific: the 2011 drought in Tuvalu, the 2012 floods in Fiji and a tropical cyclone, Evan, which devastated Samoa and Fiji in December 2012. We also relate occurrences of the extreme weather and climate events to phases of the El Niño-Southern Oscillation (ENSO) phenomenon. The impacts of such natural disasters on the countries are severe and the costs of damage are astronomical. In some cases, climate extremes affect countries to such an extent that governments declare a national state of emergency, as occurred in Tuvalu in 2011 due to the severe drought’s impact on water resources. The projected increase in the frequency of weather and climate extremes is one of the expected consequences of the observed increase in anthropogenic greenhouse gas concentration and will likely have even stronger negative impacts on the natural environment and society in the future. This should be taken into consideration by authorities of Pacific Island Countries and aid donors when developing strategies to adapt to the increasing risk of climate extremes. Here we demonstrate that the modern science of seasonal climate prediction is well developed, with current dynamical climate models being able to provide skilful predictions of regional rainfall two-three months in advance. The dynamic climate model-based forecast products are now disseminated to the National Meteorological Services of 15 island countries in the Western Pacific through a range of web-based information tools. We conclude with confidence that seasonal climate prediction is an effective solution at the regional level to provide governments and local communities of island nations in the Western Pacific with valuable assistance for informed decision making for adaptation to climate variability and change.
文摘This paper points out that delayed or no supply of software can kill potential benefits associated with new mathematical ideas that have led to development of new mathematics in OR. It also points out that it is a self-created situation by the scientific community. This situation needs attention and should be resolved urgently. Many illustrative examples have been given to justify the claim</span></span><span>.
文摘A recent trend of sea level shows constant rising. Sea level rise has caused a significant risk to seaside areas. This study examines the potential effect of climate change and rising sea levels on coastal regions and evaluates the susceptibility of coastal areas in Inverloch, Melbourne Australia. A model of Hypothetically Flooded Zones, based on LiDAR data was built, processed and manipulated in ArcGIS. Through applying this model, the effect of rising sea level on the infrastructures such as buildings, dwellings, roads, land use and the population was assessed. Elevation data sets of varying resolution and accuracy have been processed to show the improved quality of LiDAR data contributes to a more precise delineation of flood-prone coastal lands. After the susceptible areas to sea level rise were delineated, the worst-case scenario was calculated (based on the increase in sea level projected for 2100) and it would impacts about 0.86% of roads, 221 of different building infrastructures. This method can be used in other areas to protect the coasts due to rapid changes caused by climate change.
基金中国科学院科研装备研制项目(YZ201129)江苏高校优势学科建设工程项目+3 种基金Australian Space Research Program 2(ASRP2)Australian Antarctic Science Grant Program(Project4159)European Space Agency(ESA)project OPSGRAS(4000101628)Austrian National Science Fund(FWF)project BENCHCLIM(P22293-N21)资助
基金supported by the National Natural Science Foundation of China(Grant Nos.40904002 and 40804004)the China-Australia Special Fund of International Collaborative Scientific Research Project(Grant No.40911120024)+1 种基金the National Basic Research Program of China(973 Project,Grant No.2006CB701301)the National High Technology Research and Development Program of China(863 Project,Grant No.2007AA12Z339)
文摘In recent years, radio occultation (RO) technology making use of global positioning system (GPS) signals has been exploited to obtain profiles of atmospheric parameters in the neutral atmosphere. In this paper, the RO refractivity profiles obtained from the Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC) mission are statistically compared with the observations of 38 radiosonde stations provided by the Australian Bureau of Meteorology during the period from 15 July 2006 through 15 July 2007. Different collocation criteria are compared at first, and COSMIC RO soundings that occur within 3 hours and 300 km of radiosonde measurements are used for the final statistical comparison. The overall results show that the agreements between the COSMIC refractivity profiles and the radiosonde soundings from the 38 stations are very good at 0-30 km altitude, with mean absolute relative refractivity deviations of less than 0.5%. Latitudinal comparisons indicate that there are negative refractivity deviations in the lower troposphere over the low latitude and middle latitude regions and large standard deviations exist in the lower troposphere of low latitude regions, which can reach up to ~6%. The comparisons of COSMIC RO refractivity profiles and radiosonde observations for 3 polar stations in four different seasons indicate that the accuracy of GPS RO profiles is better in the Austral summer and autumn than in the Austral spring and winter during the year from September 2006 to August 2007.
基金The authors would like to thank the support by the State Key Program of National Natural Science Foundation of China under Grant[Number 41774026]the Satellite Mapping Technology and Application,National Administration of Surveying,Mapping and Geoinformation Key Laboratory under Grant[Number KLSMTA-201708].
文摘Interferometric phase filtering is one of the key steps in interferometricsynthetic aperture radar (InSAR/SAR). However, the ideal filtering results are difficult toobtain due to dense fringe and low coherence regions. Moreover, the InSAR/SAR datarange is relatively large, so the efficiency of interferential phase filtering is one of themajor problems. In this letter, we proposed an interferometric phase filtering methodbased on an amended matrix pencil and linear window mean filter. The combination ofthe matrix pencil and the linear mean filter are introduced to the interferometric phasefiltering for the first time. First, the interferometric signal is analyzed, and theinterferometric phase filtering is transformed into a local frequency estimation problem.Then, the local frequency is estimated using an amended matrix pencil at a window. Thelocal frequency can represent terrain changes, thus suggesting that the frequency can beaccurately estimated even in dense fringe regions. Finally, the local frequency is filteredby using a linear window mean filter, and the filtered phase is recovered. The proposedmethod is calculated by some matrices. Therefore, the computational complexity isreduced, and the efficiency of the interferometric phase filtering is improved.Experiments are conducted with simulated and real InSAR data. The proposed methodexhibits a better filtering effect and an ideal efficiency as compared with the traditionalfiltering method.
文摘CWD (coarse woody debris) plays an important role in nutrient cycling, habitat for species and more recently carbon accounting in forest ecosystems. LiDAR (light detection and ranging) technology has demonstrated utility in capturing forest structure information. This paper proposes an indirect method of assessing downed CWD using LiDAR derived forest structure variables. Fieldwork was conducted to measure CWD volume in an Eucalyptus forest in Tasmania. A GLM (generalized linear model) to statistically estimate CWD volume in the Eucalyptus forest was developed using a LiDAR derived FCS (forest characterisation scheme): the openings above the ground, low and medium vegetation, canopy cover, presence of understorey and mid-storey vegetation and high trees, and the vertical canopy density of high trees. Five structural variables were selected for the best model based on AIC (Akaike's Information Criterion) by stepwise selection. The applicability of the model was then compared to the outcome of model using field derived variables such as diameter at breast height of trees. The results show that the model using LiDAR derived variables better estimated the amount of CWD. It is concluded that LiDAR derived forest structural variables has the potential to predict the amount of downed CWD in Eucalyptus forest.
文摘Climate change can impact coastal areas in different ways,including flooding,storm surges,and beach erosion.Of these,flooding has a major impact on the operation of coastal drainage systems.This paper develops a new flood screening model using a LiDAR based digital elevation model(DEM)to improve the implementation of Victorian’s coastal flooding risk assessment and management.Hydrological elevation models are directed towards protection from cloudbursts and applied to rising sea level.The aim is to simulate water flow on the ground and in streams,and the resulting accumulation of water in depressions of the blue spot using DEM.Due to the presence of pipes,watercourses,bridges and channels it was required that the DEM data to be lowered.The reservoirs of rain will prevent seawater from flowing across the stream channel into land.The rain drain will be open during normal sea levels to allow rain water in the river to move and flow in to the sea.Traditionally,geographic information system(GIS)assists with spatial data management,but lacks modelling capability for complex hydrology problems and cannot be relied upon by decision-makers in this sector.Functionality improvements are therefore required to improve the processing or analytical capabilities of GIS in hydrology.This research shows how the spatial data can be primarily processed by GIS adopting the spatial analysis routines associated with hydrology.The objective of this paper is to outline the importance of GIS technology for coastal flood management.Following a definition of the coastal flood,and,short description of its peculiarities and the urgency of its management,this paper describes the use of GIS technology in coastal flood management,its advantages and the consideration for accuracy.This is followed by the information and LiDAR data required for coastal flood management and the application area in coastal flood management.This paper method is presented to conduct a first high-resolution DEM screening to detect the degree and capacities of the sinks in the coastal landscape.When their capacities are established,the rain volumes received during a rainstorm from their coastal catchments are saved as attributes to the pour points.The conclusion emphases the importance of a geographical information system in coastal flood management for efficient data handling and analysis of geographically related data.Local governments at risk of coastal flooding that use the flood screening model can use to determine appropriate land use controls to manage long-term flood risk to human settlements.
文摘Water is a basic normal asset for supporting the condition of life. Accessible water assets are feeling the squeeze because of expanding demand. Soon water, which we have depended upon to be accessible and an unconditional present of nature will turn into a rare product. Protection and conservation of water assets are desperately required. In many parts of Victoria, water supply to communities is limited. Rainwater harvesting systems can provide water at or near the point of demand. The systems can be owner and utility operated and managed. Rainwater collected using existing structures, i.e. rooftops, parking lots, playgrounds, parks, ponds, floodplains etc., has few negative environmental impacts compared to other technologies for water resources development. Rainwater is relatively clean and the quality is usually acceptable for many purposes with little or even no treatment. The physical and chemical properties of rainwater are usually superior to sources of groundwater that may have been subjected to contamination. The present study was intended to measure the rooftop rainwater harvesting potential using GIS techniques. The GIS examination utilized in this investigation was basically an efficient assessment of rooftop water collecting in the chose Wollert which is a suburb in Melbourne, Victoria. With the use of GIS it was conceivable to appraise the aggregate sum of water harvestable at the household level. It is very tedious work to assess the catchments available for rooftop rainwater harvesting. Here the roof surfaces are the catchments and GIS is employed to calculate the area of various types of roofs and their potential for planning for the area under study. As a result Eucalypt Estate Wollert has huge potential and can make above 179.11 litres water available per person per day throughout the year.
文摘Understanding urban wetland ecosystem services structure allows managers to base restoration efforts on multiple user end-benefits.Ary Creek can provide the coupled function of improving water quality and mitigating floods through delayed stormwater flow.It is fundamental to identify areas surrounded by water for the safety of individual should in case the water level raise beyond a reasonable doubt and might cause a flood.For many years,the Ary Creek catchment in Inverloch has been flooding and causing great problems for the inhabitants as well as the environment.The procedure is to develop models of the area around the catchment or watershed using Victorian Coastal LiDAR and other input data from the GIS(geographic information system).This study uses the real-time simulation in ArcSWAT—ArcGIS 10.3 and 3D in ArcScene 10.3,and the variables obtained from the soil and water assessment tool ArcSWAT such as the land use,soil and slope are the parameters measured to induce the flood.When certain portions of the Hydrologic response unit HRU,land use,soil or slope is changed due to temporal adjustment and climate change,then the model can predict zones of low,moderate and high flood risk.The 3D simulations appear to produce a visual model for decision-making,planning,management,and mitigation.The simulation helps in determining the extent of the flood by using animation.
文摘The main objective of this study is to determine how speed errors of test vehicles depend on tire pressure. In order to achieve this, experiments were conducted to find out how tire pressure depends on driving speed and how distance measurements depend on tire pressure. It is demonstrated that hot tires might have their pressure increased by 6% at 110 km/h speed relative to nominal tire pressure. Subsequently, experiments conducted on a surveyed test track proved that hot tires might increase speed measurement errors by 0.03%, whereas under-inflated tires might cause several times higher speed errors, It is critical that test vehicles involved in speed measurements have nominal tire pressure when tires are cold. In such instances, the uncertainty of speed measurements component related to tire pressure is relatively low. This research allowed quantifying the tire pressure error component for a specific test vehicle, while the experimental approach might be used for any other vehicles.
文摘The ultimate aim of using spatial datasets and spatial data modelling is focused on enabling a sustainable environment by bringing the public policies into practice. The consequence will be sustainable spatially aware strategic planning for all levels of Australian government. Geographical Information Systems (GIS) are the platform that can serve this aim provided that model, current process and spatial datasets are fit for purpose. To bring public policy into practice a broad range of knowledge from different disciplines is needed. Most decision making processes are pressured in terms of time and driving forces and also the process is beyond the knowledge of individuals in the various disciplines. There is a need for immediate uptake models and tools which are relevant to the target subject that will facilitate this decision making process. This paper focuses on realizing the utility in spatial data and spatial data handling in order to help climate change adaptation programs at local government level. Web-based mapping tools can assist planners prepare for the changing climate conditions in Bass Coast Shire Council. The GIS team has gathered data from various climate research organizations to understand projections of what different climate scenarios might look like over the next 100-year period. From this website demo it is hoped that the user will understand how the tool works, background information on different GIS platforms, access to interactive mapping, online geospatial analysis tools, videos, open source resource, sea level tools, modelling, 3D visualization and direct download access to various planning and natural resource data sets relating to environment management. Some results from our elevation data analyses through these Web map visualization tools are provided.
文摘Tropical cyclones (TCs) are the most destructive weather phenomena to impact on tropical regions, and reliable predicttion of TC seasonal activity is important for preparedness of coastal communities in the tropics. In investigating prospects for improving the skill of TC seasonal prediction in the South Indian and South Pacific Oceans, including the Australian Region, we used linear regression to model the relationship between the annual number of cyclones and three indices (SOI, NI?O3.4 and 5VAR) describing the strength of the El Ni?o-Southern Oscillation (ENSO). The correlation between the number of Australian Region (90?E - 160?E) TCs and the indices was strong (3-month 5VAR ?0.65, NI?O3.4 ?0.62 and SOI +0.64), and a cross-validation assessment demonstrated that the models which used July-August-September indices and the temporal trend as the predictors performed well. The predicted number of TCs in the Australian Region for 2010/2011 and 2011/2012 seasons was 14 (11 recorded) and 12, respectively. We also found that the correlation between the numbers of TCs in the western South Indian region (30?E to 90?E) and the eastern South Pacific region (east of 170?E) and the indices was weak, and it is therefore not sensible to build linear regression forecast models for these regions. We conclude that for the Australian Region, the new statistical model provides prospects for improvement in forecasting skill compared to the statistical model currently employed at the National Climate Centre, Australian Bureau of Meteorology. The next step towards improving the skill of TC seasonal prediction in the various regions of the Southern Hemisphere will be undertaken through analysis of outputs from the dynamical climate model POAMA (Predictive Ocean-Atmosphere Model for Australia).