Nitrogen-retaining property of compost in an aerobic thermophilic composting reactor for the sanitary disposal of human feces

Aerobic composting is a method for the sanitary disposal of human feces as is used in bio-toilet systems. As the products of composting can be utilized as a fertilizer, it would be beneficial if the composting conditions could be more precisely controlled for the retention of fecal nitrogen as long as possible in the compost. In this study, batch experiments were conducted using a closed aerobic thermophilic composting reactor with sawdust as the bulk matrix to simulate the condition of a bio-toilet for the sanitary disposal of human feces. Attention was paid to the characteristics of nitrogen transformation. Under the controlled conditions of temperature at 60°C, moisture content at 60%,anda continuous air supply, more than 70% fecal organic removal was obtained, while merely 17% fecal nitrogen loss was observed over a two-week composting period. The nitrogen loss was found to occur mainly in the first 24 h with the rapid depletion of inorganic nitrogen but with an almost unchanged organic nitrogen content. The fecal NH₄-N which was the main component of the inorganic nitrogen ( > 90%) decreased rapidly in the first day, decreased at a slower rate over the following days, and finally disappeared entirely. The depletion of NH₄-N was accompanied by the accumulation of NH₃ gas in the ammonia absorber connected to the reactor. A mass balance between the exhausted NH₃ gas and the fecal NH₄-N content in the first 24 hours indicated that the conversion of ammonium into gaseous ammonia was the main reason for nitrogen loss. Thermophilic composting could be considered as a way to keep a high organic nitrogen content in the compost for better utilization as a fertilizer.     

松辽流域生态流量赤字及其成因

水资源的过度开发导致了水短缺和水生态退化,因此,提供适宜的生态流量对维护河流健康具有重要意义.以往研究聚焦断面尺度的生态流量及其保障程度,尚未有效剥离上游子流域的影响.本研究以松辽流域为研究对象,运用VMF法、Tessmann-adapted法和Smakhtin-adapted法3种水文学法核算二级水资源区生态流量及1...     

Human Performance Cognitive-Behavioral Modeling: A Benefit for Occupational Safety

Human Performance Modeling (HPM) is a computer-aided job analysis software methodology used to generate predictions of complex humanautomation integration and system flow patterns with the goal of improving operator and system safety. The use of HPM tools has recently been increasing due to reductions in computational cost, augmentations in the tool’s fidelity, and usefulness in the generated output. An examination of an Air Man-machine Integration Design and Analysis System (Air MIDAS) model evaluating complex human-automation integration currently underway at NASA Ames Research Center will highlight the importance to occupational safety of considering both cognitive and physical aspects of performance when researching human error.     

Ergonomic Aspects of a Virtual Environment

A virtual environment is an interactive graphic system mediated through computer technology that allows a certain level of reality or a sense of presence to access virtual information. To create reality in a virtual environment, ergonomics issues are explored in this paper, aiming to develop the design of presentation formats with related information, that is possible to attain and to maintain user-friendly application.     

Force-Velocity Characteristics of Individual Human Skeletal Muscles: TBCIat and TBCIong. Outline of the Method

The aim of the work is to outline a procedure of finding force-velocity (F–V) characteristics (F = f(V)) of individual skeletal muscles of the human locomotor system. The presentation is based on an example concerning extensors of the elbow joint: the lateral and long heads of triceps brachii (TBCIat and TBCIong). The experimental part of the procedure involves a natural movement of using the upper extremity to push an external object of variable, adjustable load, engaging both the elbow and shoulder joint.

Five men aged 23 took part in the experiment. Their task was to push the handle of a physical pendulum whose moment of inertia could be adjusted within the range of 58 kg m²-450 kg m², so as to give it maximum angular velocity. During each trial the movement of the trunk, of the upper extremity and of the pendulum was video recorded and the force applied with the hand to the handle of the pendulum was measured.

In order to find the F–V characteristics a simulation model SHOULDER was used, which is capable of solving the synergy problem for muscles of the arm and the shoulder girdle.

It was found that despite considerable dispersion of experimental points the respective regression lines revealed a clear tendency of decreasing muscle force for increased shortening velocity of the monoarticular head (TBCIat) and of increasing muscle force for increased lengthening velocity of the biarticular head (TBCIong) of the triceps brachii muscle.     

A System for Measuring Vertical Concentration Profiles of Gaseous Pollutants,Using Carbon Dioxide as a Case Study

An electronically-controlled sampling system, characterised by its organ pipe design, has been developed for sampling air sequentially, at different heights within the breathing zone. Data are automatically logged at the different receptor levels, for the determination of the average vertical concentration profile of gaseous pollutants. The system has been coupled to a carbon dioxide monitor and used in a brief study of the spatial and temporal variation of indoor carbon dioxide concentration. The system can easily be extended for different heights or modified for use with other types of gas monitor. The results of a trial run, which was carried out in a coffee room, are presented and applications of the Organ Pipe Sequential Sampling (OPSS) system are discussed.     

建设用地地质灾害危险性评估的初步研究

建设用地地质灾害危险性评估是国家强制执行的工程建设工作程序之一,亦是一项起点高、难度大、操作性强的新型技术工作.本文初步分析了人类工程活动与地质灾害的关系,介绍了我国建设用地地质灾害危险性评估工作的研究现状、意义及存在的主要问题.     

Arabian,Asian, western: a cross-cultural comparison of aircraft accidents from human factor perspectives

Introduction. Rates of aviation accident differ in different regions; and national culture has been implicated as a factor. This invites a discussion about the role of national culture in aviation accidents. This study makes a cross-cultural comparison between Oman, Taiwan and the USA. Method. A cross-cultural comparison was acquired using data from three studies, including this study, by applying the Human Factors Analysis and Classification System (HFACS) framework. The Taiwan study presented 523 mishaps with 1762 occurrences of human error obtained from the Republic of China Air Force. The study from the USA carried out for commercial aviation had 119 accidents with 245 instances of human error. This study carried out in Oman had a total of 40 aircraft accidents with 129 incidences. Results. Variations were found between Oman, Taiwan and the USA at the levels of organisational influence and unsafe supervision. Seven HFACS categories showed significant differences between the three countries (p?<?0.05). Conclusion. Although not given much consideration, national culture can have an impact on aviation safety. This study revealed that national culture plays a role in aircraft accidents related to human factors that cannot be disregarded.     

地震应急避难需求的系统动力学研究

为定量研究地震应急避难人群的规模及变化规律,建立需求分析的系统动力学模型。该模型包括建筑物倒塌,断水和电梯停运3种因素造成的需求。参考汶川地震中板房建设速度和电梯修复速度,以及日本关于地震断水率的研究成果,建立非线性模型拟合各需求的变化规律。采用Vensim软件建立系统动力学模型,分析各需求的综合变化规律。采用上海市徐汇区的数据进行案例演算,并与其他研究方法对比分析仿真误差。仿真结果表明:建筑物损坏对人群数量的影响很大,但是灾后1个月内断水的影响最大;相对于工程技术因素,人因对需求有重要的影响。     

Lead astray: scale,environmental justice and the El Paso smelter

Residents in Paso del Norte (El Paso, Texas; Sunland Park, New Mexico; and Juárez, Mexico) have been concerned about heavy metal contamination in their communities since the 1970s, when high blood lead levels were found in children living in Smeltertown – a company town for the local metals smelter. After the smelter's closure in 1999, and throughout onsite and offsite cleanup efforts, residents have continued to express concerns about these contamination issues. Using a politics of scale framework and analysing ethnographic data and government, media and scientific documents, this paper identifies a set of major disjunctures between the scales of heavy metal contamination and the scales at which that contamination is regulated. These disjunctures exacerbate regional environmental injustice by complicating public participation, neglecting vulnerability and displacing hazards to new communities. Consequently, applying a politics of scale framework to this case study highlights regulatory and policy failures to address environmental justice.