A numerical model study on multi-species harmful algal blooms coupled with background ecological fields

Based on systematized physical, chemical, and biological modules, a multi-species harmful algal bloom （HAB） model coupled with background ecological fields was established. This model schematically embod-ied that HAB causative algal species and the background ecological system, quantified as total biomass, were significantly different in terms of the chemical and biological processes during a HAB while the inter-action between the two was present. The model also included a competition and interaction mechanism between the HAB algal species or populations. The Droop equation was optimized by considering tempera-ture, salinity, and suspended material impact factors in the parameterization of algal growth rate with the nutrient threshold. Two HAB processes in the springs of 2004 and 2005 were simulated using this model. Both simulation results showed consistent trends with corresponding HAB processes observed in the East China Sea, which indicated the rationality of the model. This study made certain progress in modeling HABs, which has great application potential for HAB diagnosis, prediction, and prevention.

Evaluating Traffic Congestion Using the Traffic Occupancy and Speed Distribution Relationship: An Application of Bayesian Dirichlet Process Mixtures of Generalized Linear Model

Accurate classification and prediction of future traffic conditions are essential for developing effective strategies for congestion mitigation on the highway systems. Speed distribution is one of the traffic stream parameters, which has been used to quantify the traffic conditions. Previous studies have shown that multi-modal probability distribution of speeds gives excellent results when simultaneously evaluating congested and free-flow traffic conditions. However, most of these previous analytical studies do not incorporate the influencing factors in characterizing these conditions. This study evaluates the impact of traffic occupancy on the multi-state speed distribution using the Bayesian Dirichlet Process Mixtures of Generalized Linear Models (DPM-GLM). Further, the study estimates the speed cut-point values of traffic states, which separate them into homogeneous groups using Bayesian change-point detection (BCD) technique. The study used 2015 archived one-year traffic data collected on Florida’s Interstate 295 freeway corridor. Information criteria results revealed three traffic states, which were identified as free-flow, transitional flow condition (congestion onset/offset), and the congested condition. The findings of the DPM-GLM indicated that in all estimated states, the traffic speed decreases when traffic occupancy increases. Comparison of the influence of traffic occupancy between traffic states showed that traffic occupancy has more impact on the free-flow and the congested state than on the transitional flow condition. With respect to estimating the threshold speed value, the results of the BCD model revealed promising findings in characterizing levels of traffic congestion.

Utilizing Occupancy Models and Platforms-of-Opportunity to Assess Area Use of Mother-Calf Humpback Whales

The Hawaiian Islands, and particularly the Maui 4-island region, are a critical breeding and calving habitat for humpback whales (Megaptera novaeangliae) belonging to the Hawaii distinct population segment. Our aims were to test the use of platforms-of-opportunity to determine trends in mother-calf pod use of the region and to present opportunistic platforms as an alternative method of long-term, cross-seasonal monitoring. Data were collected from whale watching vessels over a 4-year period and analyzed using occupancy models to determine the probability of habitat use of pods with calves and pods without calves within the study area. Detection probability was influenced by survey effort and month for all pod types with detection of adult only pods further influenced by year. Pods with a calf showed a preference for shallow (<100 meters) low latitude waters (<20.7°N), while pods without a calf preferred deeper waters (>75 meters). Results presented here align with previous work, both in Hawaii and in other breeding grounds, which show a distinct segregation of mothers with a calf from other age-classes of humpback whales. The need for long-term continuous monitoring of cetacean populations is crucial to ensure species conservation. Data collected aboard platforms-of-opportunity, as presented here, provide important insight on humpback whale spatial and temporal distribution, which are essential for species protection and management.

Occupancy Factor Model for Exposure to Natural Radionuclides along the Coastline of Erongo Region, Namibia

In this study, an occupancy factor model was developed and used to calculate the average time spent for outdoor and indoor activities along the coastline of the Erongo region of Namibia. A closed ended questionnaire was developed and administered to 800 respondents who visited the coastline for leisure, occupational and other activities. The mean time allocated for leisure activities ranges from 13.00 to 1.00 h, occupational mean time between 10.18 to 9.06 h and the values of other activities range from 16.66 to 11.00 h. The average computed time spent outdoor was found to be 11.46 h and indoor calculated to be 12.54 h. This shows an outdoor factor of 0.48 and indoor factor of 0.52 respectively. From the results obtained, the value of the absorbed dose rate ranged from 93.27 to 105.95 nGy·hǃ and the annual effective dose rate ranged from 121.01 to 176.61 μSv·yǃ (UNSCEAR factor) and 292.60 to 413.63 μSv·yǃ (present factor). The values obtained for annual effective dose are higher than the acceptable limit. However, from this study, we can conclude that the use of the UNSCEAR outdoor factor in the coastline will lead to underestimation of effective dose by 24% based on the present factor.

Design and Optimization for the Occupant Restraint System of Vehicle Based on a Single Freedom Model

Throughout the vehicle crash event, the interactions between vehicle, occupant, restraint system (VOR) are complicated and highly non-linear. CAE and physical tests are the most widely used in vehicle passive safety development, but they can only be done with the detailed 3D model or physical samples. Often some design errors and imperfections are difficult to correct at that time, and a large amount of time will be needed. A restraint system concept design approach which based on single-degree-of-freedom occupant-vehicle model (SDOF) is proposed in this paper. The interactions between the restraint system parameters and the occupant responses in a crash are studied from the view of mechanics and energy. The discrete input and the iterative algorithm method are applied to the SDOF model to get the occupant responses quickly for arbitrary excitations (impact pulse) by MATLAB. By studying the relationships between the ridedown efficiency, the restraint stiffness, and the occupant response, the design principle of the restraint stiffness aiming to reduce occupant injury level during conceptual design is represented. Higher ridedown efficiency means more occupant energy absorbed by the vehicle, but the research result shows that higher ridedown efficiency does not mean lower occupant injury level. A proper restraint system design principle depends on two aspects. On one hand,the restraint system should lead to as high ridedown efficiency as possible, and at the same time, the restraint system should maximize use of the survival space to reduce the occupant deceleration level. As an example, an optimization of a passenger vehicle restraint system is designed by the concept design method above, and the final results are validated by MADYMO, which is the most widely used software in restraint system design, and the sled test. Consequently, a guideline and method for the occupant restraint system concept design is established in this paper.

Dopant Occupancy in MgO-Codoped Lithium Niobate Crystals

On the basis of the bond valence model, the preferential occupancy of various dopant such as Mn2+, Eu3+, Er3+, Nd3+, Lu3+, Yb3+, In3+, Cr3+, Fe3+ and Ti4+ in the ideal stoichiometric lithium niobate (SLN) crystallographic frame was investigated in a viewpoint of chemical bonds. Theoretical analysis indicates that the dopant occupancy is significantly influenced by the anti-site Nb4+Li. Our work also shows that Mg-like ions (Mg2+, Zn2+, In3+, Sc3+) have a repulsive effect on Nb4+Li ions. When removing Nb4+Li ion by codoping Mg-like ions, the dopant occupancy in the LN crystallographic frame is determined by the natural characteristics of dopant, which is consistent well with the result in the ideal SLN crystals.

Development of Job Burden-capital Model of Occupational Stress： An Exploratory Study

This study proposes a new framework as job burden-capital model for comprehensive assessment on occupational stress. 1618 valid samples were recruited from electronic manufacturing service industry in Hunan province by self-rated questionnaires after written consent. Structural equation model analysis was employed to verify the model by the data collected. The final fitting model has satisfactory fitting goodness （CMIN/DF=5.78, AGFI=0.937, NNFI=0.960, IF1=0.968, RMSEA=0.054）. Both of the measurement model and structural model have acceptable path Ioadings. Job burden and capital could either directly affect occupational outcomes or indirectly influence them through equation personality.

基于CFD−DPM的空气幕协同排风罩增效除尘研究

以某机械厂打磨车间为研究对象,利用Solidworks软件建立带有空气幕协同排风罩除尘的打磨车间模型,基于气固两相流理论,采用计算流体力学离散颗粒模型(CFD−DPM)模拟分析空气幕送风速度、射流角度和射流宽度对除尘效率的影响,选取空气幕的最优参数;在此基础上,对比分析未开启排风罩、开启排风罩、同时开启排风罩与空气幕3种工况的风速分布、粉尘运移轨迹及粉尘质量浓度分布,探讨空气幕协同排风罩除尘的效果。结果表明:粉尘最大浓度、呼吸带粉尘浓度随空气幕送风速度、射流宽度的增大而减小,但不随空气幕射流角度的变化而变化;粉尘浓度随地面高度的增大先增后减,不同高度处粉尘浓度变化趋势基本一致;当空气幕射流宽度30 mm、射流角度30°、送风速度3 m/s时,通风除尘效果最佳,除尘效率高达94.2%。相比于仅开启排风罩,排风罩与空气幕协同作用下的除尘效率提高了38.8%,空气幕协同排风罩对车间除尘具有较好的增效作用。

基于建筑高度和地层厚度的城市地下空间占用深度快速评估方法——以杭州市为例

城市高密度的建筑物事实上占据了位于其下部一定深度的地下空间资源,其占用深度对城市地下空间(UUS)网络化开发具有重要影响,因此,在UUS规划前,需要掌握规划范围内地下空间占用深度和空间分布格局。UUS占用深度除地下建筑物深度外还包括下部地基持力层深度,其与建筑高度和场地地质条件相关。笔者等提出基于建筑高度和地层厚度的UUS占用深度快速评估方法,以杭州主城区为研究对象,通过实测建筑高度数据和收集建筑基础数据建立评估数学模型,利用百度建筑数据和杭州三维地质模型生成的地层厚度数据,并基于GIS平台的空间分析,实现了对杭州市主城区建筑地下空间占用深度的快速评估。研究成果为城市地下空间规划所需的大范围地下空间占用情况提供了高效的评估手段。

Simulation of Restraint System Performance upon the Occupant's Response During Impact

Aim To study the influence of restraint system performance upon the occupant's response during impact, and provide a scientific base for occupant restraint system design. Methods \ In the light of basic theory of multibody system dynamics and impact dynamics on the basis of classical theory of impact, R W method is adopted to construct the vehicle occupant system model consisting of fourteen rigid bodies, thirty seven DOFs and slip joints for the simulation. A software named SVC3D(3 dimensional simulation of vehicle crash) is developed in the FORTRAN language. Results\ The results of simulation have a good coincidence with those of tests and the restraint system with low elongation webbing and equipped with pretensioner provides better restraint effect for the occupant. Conclusion\ The model of vehicle occupant multibody system and SVC3D are suitable for use. Occupant should be belted with low elongation webbing to a certain degree and occupant restraint system should be equipped with pretensioner.

三种典型森林雉类的占域模式及影响因子

凉山山系马边大风顶国家级自然保护区山地森林内共存着多样性极为丰富的雉类物种,为了了解这些雉类的占域率、种间相互作用及其影响因子,于2021年5月至2023年6月,在该保护区内布设了131台红外相机,累计工作37 496相机日,对3种典型森林雉类红腹角雉(Tragopan temminckii,独立有效拍摄n=593)、血雉(Ithaginis cruentus,n=227)、白鹇(Lophura nycthemera,n=81)进行了监测,并使用多物种占域模型分析不同因子对其占域的影响。结果显示:3种雉类的占域率受不同环境变量的影响,即红腹角雉的占域率与海拔、坡度、草本盖度和灌木均高呈正相关,与距水源距离、人类活动强度和放牧强度呈负相关;血雉的占域率与坡向、坡度、海拔、距水源距离、乔木均高、灌木均高和草本盖度呈正相关,与人类活动强度呈负相关;白鹇的占域率与坡向呈正相关,与海拔、坡度、乔木均高、灌木均高、草本盖度和放牧强度呈负相关。红腹角雉和血雉之间具有负相互作用,红腹角雉和白鹇、血雉和白鹇之间具有正相互作用。3种雉类两两之间的相互作用对其占域率影响的重要性均大于栖息地特征和人为干扰。综上,种间相互作用、栖息地特征和人为干扰共同影响了凉山山系3种森林雉类的占域和共存。基于研究结果,建议保护区在开展多物种整合保护时,加强对物种之间相互作用的评估和对雉类栖息地内的人为活动和干扰的管控。

Investigation of the role of personal factors on work injury in underground mines using structural equation modeling

Work injuries in mines are complex and generally characterized by several factors starting from personal to technical and technical to social characteristics.In this paper,investigation was made through the application of structural equation modeling to study the nature of relationships between the influencing/associating personal factors and work injury and their sequential relationships leading towards work injury occurrences in underground coal mines.Six variables namely,rebelliousness,negative affectivity,job boredom,job dissatisfaction and work injury were considered in this study.Instruments were developed to quantify them through a questionnaire survey.Underground mine workers were randomly selected for the survey.Responses from 300 participants were used for the analysis.The structural model of LISREL was used to estimate the interrelationships amongst the variables.The case study results show that negative affectivity and job boredom induce more job dissatisfaction to the workers whereas risk taking attitude of the individual is positively influenced by job dissatisfaction as well as by rebelliousness characteristics of the individual.Finally,risk taking and job dissatisfaction are having positive significant direct relationship with work injury.The findings of this study clearly reveal that rebelliousness,negative affectivity and job boredom are the three key personal factors influencing work related injuries in mines that need to be addressed properly through effective safety programs.

Establishment and Validation for the Theoretical Model of the Vehicle Airbag

The current design and optimization of the occupant restraint system（ORS） are based on numerous actual tests and mathematic simulations. These two methods are overly time-consuming and complex for the concept design phase of the ORS, though they＇re quite effective and accurate. Therefore, a fast and directive method of the design and optimization is needed in the concept design phase of the ORS. Since the airbag system is a crucial part of the ORS, in this paper, a theoretical model for the vehicle airbag is established in order to clarify the interaction between occupants and airbags, and further a fast design and optimization method of airbags in the concept design phase is made based on the proposed theoretical model. First, the theoretical expression of the simplified mechanical relationship between the airbag＇s design parameters and the occupant response is developed based on classical mechanics, then the momentum theorem and the ideal gas state equation are adopted to illustrate the relationship between airbag＇s design parameters and occupant response. By using MATLAB software, the iterative algorithm method and discrete variables are applied to the solution of the proposed theoretical model with a random input in a certain scope. And validations by MADYMO software prove the validity and accuracy of this theoretical model in two principal design parameters, the inflated gas mass and vent diameter, within a regular range. This research contributes to a deeper comprehension of the relation between occupants and airbags, further a fast design and optimization method for airbags＇ principal parameters in the concept design phase, and provides the range of the airbag＇s initial design parameters for the subsequent CAE simulations and actual tests.

Potential distributional shifts in North America of allelopathic invasive plant species under climate change models

Predictive studies play a crucial role in the study of biological invasions of terrestrial plants under possible climate change scenarios.Invasive species are recognized for their ability to modify soil microbial communities and influence ecosystem dynamics.Here,we focused on six species of allelopathic flowering plants-Ailanthus altissima,Casuarina equisetifolia,Centaurea stoebe ssp.micranthos,Dioscorea bulbifera,Lantana camara,and Schinus terebinthifolia-Xhat are invasive in North America and examined their potential to spread further during projected climate change.We used Species Distribution Models(SDMs)to predict future suitable areas for these species in North America under several proposed future climate models.ENMEval and Maxent were used to develop SDMs,estimate current distributions,and predict future areas of suitable climate for each species.Areas with the greatest predicted suitable climate in the future include the northeastern and the coastal northwestern regions of North America.Range size estimations demonstrate the possibility of extreme range loss for these invasives in the southeastern United States,while new areas may become suitable in the northeastern United States and southeastern Canada.These findings show an overall northward shift of suitable climate during the next few decades,given projected changes in temperature and precipitation.Our results can be utilized to analyze potential shifts in the distribution of these invasive species and may aid in the development of conservation and management plans to target and control dissemination in areas at higher risk for potential future invasion by these allelopathic species.

Predictors of work injury in underground mines—an application of a logistic regression model

Mine accidents and injuries are complex and generally characterized by several factors starting from personal to technical, and technical to social characteristics.In this study, an attempt has been made to identify the various factors responsible for work related injuries in mines and to estimate the risk of work injury to mine workers.The prediction of work injury in mines was done by a step-by-step multivariate logistic regression modeling with an application to case study mines in India.In total, 18 variables were considered in this study.Most of the variables are not directly quantifiable.Instruments were developed to quantify them through a questionnaire type survey.Underground mine workers were randomly selected for the survey.Responses from 300 participants were used for the analysis.Four variables, age, negative affectivity, job dissatisfaction, and physical hazards, bear significant discriminating power for risk of injury to the workers, comparing between cases and controls in a multivariate situation while controlling all the personal and socio-technical variables.The analysis reveals that negatively affected workers are 2.54 times more prone to injuries than the less negatively affected workers and this factor is a more important risk factor for the case-study mines.Long term planning through identification of the negative individuals, proper counseling regarding the adverse effects of negative behaviors and special training is urgently required.Care should be taken for the aged and experienced workers in terms of their job responsibility and training requirements.Management should provide a friendly atmosphere during work to increase the confidence of the injury prone miners.

Multiproduct and multistage integrated production planning model and algorithm based on an available production capacity network

This research attempts to devise a multistage and multiproduct short-term integrative production plan that can dynamically change based on the order priority and virtual occupancy for application in steel plants. Considering factors such as the delivery time, varietal compatibility between different products, production capacity of variety per hour, minimum or maximum batch size, and transfer time, we propose an available production capacity network with varietal compatibility and virtual occupancy for enhancing production plan implementation and quick adjustment in the case of dynamic production changes. Here available means the remaining production capacity after virtual occupancy.To quickly build an available production capacity network and increase the speed of algorithm solving, constraint selection and cutting methods with order priority were used for model solving. Finally, the genetic algorithm improved with local search was used to optimize the proposed production plan and significantly reduce the order delay rate. The validity of the proposed model and algorithm was numerically verified by simulating actual production practices. The simulation results demonstrate that the model and improved algorithm result in an effective production plan.

New approaches to cognitive work analysis through latent variable modeling in mining operations

This paper discusses the utilization of latent variable modeling related to occupational health and safety in the mining industry.Latent variable modeling,which is a statistical model that relates observable and latent variables,could be used to facilitate researchers’understandings of the underlying constructs or hypothetical factors and their magnitude of effect that constitute a complex system.This enhanced understanding,in turn,can help emphasize the important factors to improve mine safety.The most commonly used techniques include the exploratory factor analysis(EFA),the confirmatory factor analysis(CFA)and the structural equation model with latent variables(SEM).A critical comparison of the three techniques regarding mine safety is provided.Possible applications of latent variable modeling in mining engineering are explored.In this scope,relevant research papers were reviewed.They suggest that the application of such methods could prove useful in mine accident and safety research.Application of latent variables analysis in cognitive work analysis was proposed to improve the understanding of human-work relationships in mining operations.

Recent Trends in Occupational Injuries and Diseases in Argentina: A Panel Data Approach

Occupational injuries pose major public health and development related problems. However, efforts towards identification of determinants of labor incidents among salaried workers are still scarce in developing countries. This study aimed to identify sector and time effects on occupational accidents and diseases among Argentinean workers during 2004-2013. A negative binomial panel data model is estimated based on official data on injuries and fatalities in workplaces collected by the Board of Occupational Risks. Business cycle and profitability indicators are used as explanatory variables. Estimations also are adjusted by sector and time effects. Argentina business cycle tends to be negatively related with occupational injuries rates. In contrast, accidents at work reported tend to exhibit longer losses in working days. We also find a positive relationship between profitability and fatal injuries. These results may suggest incentives for under reporting and lower investments in safety by more profitable activities, which can imply some level of endogeneity between profit rate and occupational injuries.

The development and evaluation of a nurse anaesthesia model for practice in South Africa

Objective This article aimed to present a developed model for nurse anaesthesia practice in South Africa and then to evaluate the model by national and international anaesthetist experts.Methods For the model development,a theory-generative research design was used as guided by Chinn&Kramer.The study included four steps to develop and evaluate the model:step one,concept analysis;step two,placing the concepts into relationships;step three,description and critical reflection of the model;step four,evaluation of the model.For evaluation of the model,data were collected using individual,in-depth interviews.Four South African medical specialist anaesthesiologists and four international nurse anaesthetists were interviewed.Transcribed interviews were analyzed using Tesch’s eight steps of thematic data analysis.Results The model was described in four phases:relationship phase,working phase,termination phase,and independent phase.The model shows a development process of a student nurse anaesthetist by a nurse anaesthetist facilitator to the mastery of the scope of practice of a nurse anaesthetist.Two themes(six categories)emerged through thematic analysis:the model and guidelines for implementation were found to be appropriate(model and guidelines for implementation are important because of the need for nurse anaesthetist,the model is applicable because it is described as comprehensive,the relationship phase was found to be important and the interdependence between disciplines is imperative,the affirmation that mastery has to be attained by nurse anaesthetists due to the complexity of services rendered),anticipated limitations to the South African nurse anaesthetist(the need to identify complex patients and limitations on the setting and refer to higher level of care,limitations due to red tape).Conclusions This model provides fertile soil to inform and outline the education(curriculum)and practice(scope of practice)and research for nurse anaesthesia practice in South Africa.

On Evaluating the Efficacy of Predictive Models for Cognitive Radio Spectrum Availability in Nigeria

In order to avoid the undesired interference with the activities of the primary users in cognitive radio networks, the secondary users are required to be able to predict the behavior of the primary users so as to leave the channel before the arrival of such licensed owner of the spectrum. While a number of existing literatures on cognitive radio spectrum prediction employ the use of propagation curves for predicting the spectrum holes otherwise known as TV white space, these models are built based on measurements conducted in regions that are different from Nigeria, suitability in terms of usage may therefore vary due to environmental factors and terrain profile. This work evaluates the efficacy of the developed model in predicting the cognitive spectrum availability in Nigeria. Models capable of predicting spectrum occupancy in the time domain using discrete-time two-state Markov chain with an appropriate Duty Cycle (DC) model and also a modified m-bell shaped exponential equation were formulated. The result obtained in all cases considered shows that the formulated models are appropriate to be used in any environment if the parameters were carefully extracted from the data. This work has also demonstrated that the accuracy of Markov chain models depends on the level of usage of a spectrum under consideration and may therefore not give desirable results when employed in some other spectrum.