Equivalent protection factor of bi-layer ceramic metal structures

With increasing ballistic threat levels,there is ever more demand on developing ceramic armor designs with improved performance.This paper presents finite element simulations that investigate the performance of silicon carbide ceramic with steel 4340 backing material and titanium alloy,graphite as buffer layers when subjected to normal and oblique impacts by a tungsten alloy long rod projectile(LRP).Depth of penetration from experimental measurements is compared with simulations to confirm the validity of constitutive,failure model parameters.Titanium alloy cover plate and graphite interface weak layer laterally spread the impact shock away from the SiC tile and reduces the amplification of the stress accumulation at the front surface of the SiC tile.The dwelling time increases before it penetrates into ceramic armor.Further,using AUTODYN®numerical simulations detailed parametric study is carried out to identify the minimum areal density armor for a given ballistic limit velocity.The equivalent protection factor for the bi-layer armor is a simple function of the cosine of the angle of impact.

Impacts of automated passenger cars on the capacity of a freeway basic section: applicability in the determination of vehicle adjustment factors in mixed traffic

The highway capacity manual(HCM)provides a formula to calculate the heavy vehicle adjustment factor(fHV)as a function of passenger car equivalent factors for the heavy vehicle(ET).However,a significant drawback is that the methodology was established solely based on human-driven passenger cars(HDPC)and human-driven heavy vehicles(HDHV).Due to automated passenger cars(APCs),a new adjustment factor(fAV)might be expected.This study simulated traffic flows at different percentages of HDHVs and APCs to investigate the impacts of HDHVs and APCs on freeway capacity by analyzing their influence on fHV and fAV values.The simulation determined observed adjustment factors at different percentages of HDHVs and APCs(fobserved).The HCM formula was used to calculate(fHCM).Modifications to the HCM formula are proposed,and vehicle adjustment factors due to HDHVs and APCs were calculated(fproposed).Results showed that,in the presence of APCs,while fobserved and fHCM were statistically significantly different,fobserved and fproposed were statistically equal.Hence,this study recommends using the proposed formula when determining vehicle adjustment factors(fproposed)due to HDHVs and APCs in the traffic stream.

Spatiotemporal Evolution of Ecosystem Service Value in Caohai National Nature Reserve

Wetland ecosystems are important regulators of global climate change.Studying the spatiotemporal changes and driving mechanisms of their ecosystem service values(ESV)is beneficial for the sustainable development of wetlands.This paper uses the equivalent factor method,based on land use changes,to reveal the spatiotemporal evolution of the ecosystem service value in the Caohai National Nature Reserve(CNNR).The results show the following:①from 2000 to 2020,there was a significant decrease in the core zone s arable land area,with an increase in forest and water areas.Construction land mainly increased in the experimental area,and the grassland area showed a fluctuating change of first increasing and then decreasing;②in 2000,2010,and 2020,the ecosystem service value of the study area was 302 million,296 million,and 325 million yuan,respectively,showing a trend of fluctuating growth,with the value of wetland ecosystems playing a dominant role;③regulatory services are the main contributors to the ecosystem service value in the study area,with a contribution rate of 60%.Hydrological regulation is the ecosystem function with the highest value in wetland ecosystem services,contributing more than 35%to the ESV in all three periods;④in terms of spatial distribution,the core zone s ecosystem service value is dominant.Looking at the total ecosystem service value of the region,the core zone>the experimental area>the buffer zone.In terms of ESV per unit area,the core zone(89000 yuan/hm^(2))is significantly higher than the buffer zone(39100 yuan/hm^(2))and the experimental area(15800 yuan/hm^(2)).The study can provide a basis for research and spatial management of ecosystem services in wetland ecosystems and nature reserves.

Estimation of Passenger Car Equivalents for Basic Freeway Sections at Different Traffic Conditions

Passenger car equivalent (PCE) is an important factor which is used to convert traffic volumes containing proportions of heavy good vehicles (HGVs) to a unify measure containing only passenger cars units (PCU). This paper uses large data base of real traffic raw data extracted from loop detector before being aggregated to estimate PCEs. These detectors are located on the M25 and the M42 motorway sites in the United Kingdom. The selected sites represent basic freeway segments as they are far away from the influence of entrance (on ramp) and exit (off ramp) sections. The data are filtered properly so as to estimate passenger car equivalents (PCEs) using lagging headway method for close following situations at different speed ranges. The results suggest that for the same location, the equivalency factors are varies significantly based traffic speed. However, it is proved that such variation with traffic speed is influenced by the differences in lengths between HGVs and cars. Regression models have also been developed linking the PCEs with traffic speed.

Application of Ecological Footprint Method Based on Net Primary Productivity in Inner Mongolia

Using ecological footprint method based on net primary productivity （NPP）, the ecological footprint, ecological carrying capacity and ec- ological deficit/surplus in Inner Mongolia in 2005 and 2010 were calculated firstly, and then their temporal and spatial variations were analyzed. Fi- nally, the main driving factors of changes in the ecological footprint were discussed through linear regression analysis. The results show that the ec- ological footprint increased faster than the ecological carrying capacity in Inner Mongolia from 2005 to 2010, and Inner Mongolia was in ecological deficit on the whole. In addition, the ecological state became worse from the northeast to the southwest in Inner Mongolia, and the ecological state was the worst in Ordos City where the ecological deficit reached 0.9 km2/capita in 2010. As a result of increase of industrial intensity and unreason- able industrial structure, the sustainability in Inner Mongolia decreased.

Ecosystem service values of gardens in the Yellow River Basin,China

Studies on the ecosystem service value(ESV)of gardens are critical for informing evidence-based land management practices based on an understanding of the local ecosystem.By analyzing equivalent value factors(EVFs),this paper evaluated the values of 11 ecosystem services of gardens in the Yellow River Basin of China in 2019.High-precision land use survey data were used to improve the accuracy of the land use classification,garden areas,and spatial distribution of the ESVs of gardens.The results showed that garden ecosystem generally had high ESVs,especially in terms of the ESV of food production,which is worthy of further research and application to the practice of land use planning and management.Specifically,the value of one standard EVF of ecosystem services in 2019 was 3587.04 CNY/(hm^(2)·a),and the ESV of food production of gardens was much higher than that of croplands.Garden ecosystem provided an ESV of 1348.66×10^(8)CNY/a in the Yellow River Basin.The areas with the most concentrated ESVs of gardens were located in four regions:downstream in the Shandong-Henan zone along the Yellow River,mid-stream in the Shanxi-Shaanxi zone along the Yellow River,the Weihe River Basin,and upstream in the Qinghai-Gansu-Ningxia-Inner Mongolia zone along the Yellow River.The spatial correlation of the ESVs in the basin was significant(global spatial autocorrelation index Moran's I=0.464),which implied that the characteristics of high ESVs adjacent to high ESVs and low ESVs adjacent to low ESVs are prominent.In the Yellow River Basin,the contribution of the ESVs of gardens to the local environment and economy varied across regions.We also put forward some suggestions for promoting the construction of ecological civilization in the Yellow River Basin.The findings of this study provide important contributions to the research of ecosystem service evaluation in the Yellow River Basin.

Study on Hysteretic Bond Mechanisms of Plain Round Bar

Plain round bars were commonly used as main bars in the design of RC （reinforced concrete） buildings prior to the 1970s. According to previous research investigating the seismic performance of reinforced concrete members constructed with plain round bars, the strength of those members did not reach the calculated flexural strength due to bond slippage of main bars before yielding. It is important, therefore, to investigate the hysteretic bond mechanisms of plain round bars in concrete. In this research, analytical models were proposed to predict hysteretic bond-slip mechanisms between plain round bar and concrete depending on the results of experiments performed by the authors. In addition, the energy absorption capacity and the equivalent viscous damping factors obtained from the experimental results and analytical models are discussed. As a result of comparisons between the experimental data and the analysis models, good agreements were obtained.

The calculation of equivalence factor for ecological footprints in China： a methodological note

The Ecological Footprint （EF）, a physical indicator to measure the extent of humanity＇s use of natural resources, has gained much attention since it was first used by Wackemagel and Rees in 1996. In order to appraise land area types with different levels of productiv- ity, they introduced the concept of an equivalence factor. This relates to the average primary biomass productivities of different types of land （i.e. arable land, pasture, forest, water/fishery, built-up land and fossil energy land） to the regional average primary biomass productivity of all land types in a given year. Hence, the equivalence factor is an important parameter in the EF model and it directly affects the reliability of all results. Thus, this article calculates equivalence factors on the national and provincial levels in China based on Net Primary Production （NPP） from MODIS 1 km data in 2008. Firstly, based on the Light Utility Efficiency and CASA model, the NPP of different biologically productive lands of China and of different provinces was calculated. Secondly, China＇s equivalence factor for 6 land area types was calculated based on NPP： arable land and built-up land has an equivalence factor of 1.71, forest and fossil energy land has a factor of 1.41, pasture has a factor of 0.44 and water/fishery 0.35; Finally, the equivalence factor of 6 land area types in different provinces was also calculated. The NPP of each ecosystem type varies along with the equivalence factor in different provinces. However, the ranking of the equivalence factors in different provinces remain the same, with that of arable land being the largest, and the water/fishery being the smallest.

Carbon emission reduction analysis of CHP system driven by biogas based on emission factors

The cogeneration system of heat,power,and biogas(CHPB)driven by renewable energy provides an effective solution for carbon emission reduction in rural China.Starting from fully meeting the energy demand of 17 new rural residential households in Lanzhou,considering the annual dynamic local climate change,energy consump-tion characteristics,and environment parameters,a model of environmental benefit index for the CHPB system is constructed.The concept of emission factor is used to quantitatively analyze the environmental benefits of the system.The equivalent CO_(2)emission factor is defined to connect emissions with energy output,evaluating the environment-friendly potential of energy supply system.Compared with the conventional systems of indepen-dent power and thermal generation,the year-round characteristics of CO_(2)emission and emission structure chart of the proposed system are analyzed.The results show that the total CO_(2)emission and the average equivalent CO_(2)emission factors of the conventional and CHPB system are 85.45t,1.53 kg/kWh,and 308.46t,0.22 kg/kWh,respectively.The maximum CO_(2)emission reduction ratio of the CHPB system is 113.47%.Anaerobic digestion technology is employed to consume biomass feedstock,which reduced CH_(4)emission(equivalent to 86.36t of CO_(2)emission reduction).Five typical cities were selected to study the regional adaptability of the system and analyze environmental benefits.The results indicate that the CHPB system has the best environmental performance in Guangzhou,where the average CO_(2)emission reduction rate is 103.52%.

Gender-and Age-Group Specific Association of Persistent Organic Pollutants(POPs)Exposure with Diabetes Mellitus:Korean National Environmental Health Survey(KoNEHS)2015−2017

Exposure to persistent organic pollutants(POPs)has been reported as a potential risk factor for diabetes in adults.However,effect modifications by sex and age,especially among Asian populations,have seldom been investigated.In the present study,we assessed associations of major POPs exposure including organochlorine pesticides(OCPs),polychlorinated biphenyls(PCBs),and polybrominated diphenyl ethers(PBDEs),with diabetes in Korean adults(n=1,295),a subset of the Korean National Environmental Health Survey(KoNEHS)Cycle 3(2015−2017).In the adult population,serum levels of dichlorodiphenyltrichloroethanes(DDTs)and PCB167 showed an increased odds ratio(OR)for diabetes.When stratified by gender,associations became stronger and more consistent in women:In women,serum levels of OCPs including p,p′-DDT,p,p′-dichlorodiphenyldichloroethylene(p,p′-DDE),andΣOCPs and mono-ortho PCBs,such as PCB118 and PCB157,were significantly associated with diabetes.In the male participants,however,no significant positive associations were detected.When stratified by a cutoff age of 50 years,most studied POPs except PBDEs,i.e.,p,p′-DDT,p,p′-DDE,PCB118,PCB157,PCB167,PCB138,and PCB153,showed significant associations with diabetes,in the older adults.In the younger group,however,no measured POPs showed a significant positive association.Effects of endogenous sex hormones or interaction of POPs on aryl hydrocarbon receptors may partly explain the observed differences by gender and age,although further experimental confirmations should follow.Our findings show that POPs exposure at the current levels is associated with diabetes among general Korean adults,and such associations could be modified by gender and age.

Remote monitoring system for real time detection and classification of transmission line faults in a power grid using PMU measurements

Remote monitoring of transmission lines of a power system is significant for improved reliability and stability during fault conditions and protection system breakdowns.This paper proposes a smart backup monitoring system for detecting and classifying the type of transmission line fault occurred in a power grid.In contradiction to conventional methods,transmission line fault occurred at any locality within power grid can be identified and classified using measurements from phasor measurement unit(PMU)at one of the generator buses.This minimal requirement makes the proposed methodology ideal for providing backup protection.Spectral analysis of equivalent power factor angle(EPFA)variation has been adopted for detecting the occurrence of fault that occurred anywhere in the grid.Classification of the type of fault occurred is achieved from the spectral coefficients with the aid of artificial intelligence.The proposed system can considerably assist system protection center(SPC)in fault localization and to restore the line at the earliest.Effectiveness of proposed system has been validated using case studies conducted on standard power system networks.

Availability Equivalence Analysis of a Repairable Multi-State Series-Parallel System

The availability equivalence of different designs for a repairable multi-state series-parallel system(RMSPS) is discussed in this paper.The system components are assumed to be independent,and their failure and repair rates to be constant.The system availability is defined as the ability of the system to satisfy consumer demand.Factor improvement method and standby redundancy method are used to improve the system design.To evaluate availability of the both original and improved systems,a fast technique,based on universal generating function,is adopted.The availability equivalence factor is introduced to compare different system designs.Two types of availability equivalence factors of the system are derived.A numerical example is provided to illustrate how to utilize the obtained results.

Reliability prediction and its validation for nuclear power units in service

In this paper a novel method for reliability prediction and validation of nuclear power units in service is proposed. The equivalent availability factor is used to measure the reliability, and the equivalent availability factor deducting planed outage hours from period hours and maintenance factor are used for the measurement of inherent reliability. By statistical analysis of historical reliability data, the statistical maintenance factor and the undetermined parameter in its numerical model can be determined. The numerical model based on the main- tenance factor predicts the equivalent availability factor deducting planed outage hours from period hours, and the planed outage factor can be obtained by using the planned maintenance days. Using these factors, the equivalent availability factor of nuclear power units in the following 3 years can be obtained. Besides, the equivalent availability factor can be predicted by using the historical statistics of planed outage factor and the predicted equivalent avail- ability factor deducting planed outage hours from period hours. The accuracy of the reliability prediction can be evaluated according to the comparison between the predicted and statistical equivalent availability factors. Furthermore, the reliability prediction method is validated using the nuclear power units in North American Electric Reliability Council （NERC） and China. It is found that the relative errors of the predicted equivalent availability factors for nuclear power units of NERC and China are in the range of-2.16% to 5.23% and -2.15% to 3.71%, respectively. The method proposed can effectively predict the reliability index in the following 3 years, thus providing effective reliability management and mainte- nance optimization methods for nuclear power units.