Exercise and the cold

The generation of heat by the human body has been likened to that of a furnace. In response to winter conditions or prolonged immersion in cold water, heat may be lost from the body more quickly than it is produced leading to hypothermia. Various factors, environmental and individual, predispose a person to hypothermia when walking on dry land or during cold water immersion. Retention of the insulating properties of the clothing worn is of crucial importance in protecting against cold injury both on land and in water. Anthropometric characteristics and behavioural and physiological responses also influence the probability of survival under these conditions. Practical recommendations for behaviour that will enhance survival during prolonged exposure to cold on land or to immersion in cold water are considered.     

嵌入式软件加载与运行时域分析

介绍了嵌入式开发环境ADS1．2的参数设置与AXD的调试方法．通过一个简单的实例调试说明了参数设置对嵌入式软件的加载和运行时域的影响。     

A comparison of time to exhaustion at [vdot]O2;max in elite cyclists,kayak paddlers,swimmers and runners

Abstract

A recent study has shown the reproducibility of time to exhaustion (time limit: ttime) at the lowest velocity that elicits the maximal oxygen consumption (υ[vdot]O₂ max). The same study found an inverse relationship between this time to exhaustion at υ[vdot]O₂ max and υ[vdot]O₂ max among 38 élite long-distance runners (Billat et al. 1994b). The purpose of the present study was to compare the time to exhaustion at the power output (or velocity) at [vdot]O₂ max for different values of [vdot]O₂ max, depending on the type of exercise and not only on the aerobic capacity. The time of exhaustion at υ[vdot]O₂ max (tlim) has been measured among 41 élite (national level) sportsmen: 9 cyclists, 9 kayak paddlers, 9 swimmers and 14 runners using specific ergometers. Velocity or power at [vdot]O₂ max ( υ[vdot]O₂ max) was determined by continuous incremental testing. This protocol had steps of 2 min and increments of 50 W, 30 W, 0.05ms^? and 2km^? for cyclists, kayak paddlers, swimmers and runners, respectively. One week later, dim was determined under the same conditions. After a warm-up of 10 min at 60% of their υ[vdot]O₂ max, subjects were concluded (in less than 45 s) to their υ[vdot]O₂ max and then had to sustain it as long as possible until exhaustion. Mean values of υ[vdot]O₂ max and dim were respectively equal to 419±49 W (tlim = 222 ± 91 s), 239±56W ( tlim = 376 ± 134 s), l 46±009ms^?1 ( tlim = 287± 160s) and 22.4 ±0.8kmh^?1 ( tlim = 321 ±84s), for cyclists, kayak paddlers, swimmers and runners. Time to exhaustion at υ[vdot]O₂ max was only significantly different between cycling and kayaking (ANOVA test, p<0.05). Otherwise, υ[vdot]O₂max (expressed in ml min^?1 kg^?1) was significantly different between all sports except between cycling and running (p < 0.05). In this study, time to exhaustion at υ[vdot]O₂ max was also inversely related to υ[vdot]O₂ max for die entire group of elite sportsmen (r= ?0.320, p<0.05, n = 41). The inverse relationship between υ[vdot]O₂ max and dim at υ[vdot]O₂ max has to be explained, it seems that dim depends on υ[vdot]O₂ max regardless of the type of exercise undertaken.     

Characterizing the anthropometric extremes of the population

Equipment designers frequently choose 5 percentile female and 95 percentile male dimensions as design limits. However, in the more complex design problems which involve several body dimensions, it is important also to consider the interactions or relationships between body dimensions. These have been investigated using data from an anthropometric survey, which was carried out by MIRA, in order to develop models which represent the extreme body sizes of the male and female population.     

Biomechanical and physiological comparison of conventional webbing and the M83 assault vest

This study compared the effect of load distribution using two different webbing designs on oxygen consumption and running kinematics of soldiers. It was hypothesised that running with webbing that distributes the load closer to the body (M83 Assault Vest) would expend less energy compared to running with conventional webbing (CON). Seven soldiers randomly completed three treadmill trials; an unloaded VO(2)max test, and two loaded (8 kg) efficiency tests using either the M83 or CON webbing. The VO(2)max test and the loaded efficiency tests had 4-min stages at 5, 8, 10 and 12 km h(-1). Energy expenditure was measured via indirect calorimetry and video analysis was used to determine stride frequency (SF) and stride length (SL) during each trial. Participants using the M83 webbing expended significantly (p<0.05) less energy at all four running velocities compared to the CON trials. The M83 webbing resulted in smaller changes to SL and SF from the unloaded trial when compared to the CON trial. These results indicate that the M83 vest that is designed to distribute the load closer to the body may have an energy efficiency advantage over conventional webbing when soldiers are running.     

电机车自动定位运行控制系统

本文提出了一种基于AT89S52单片机的电机车半自动运行控制系统的实用开发方法。介绍了由AT89S52单片机根据来自炉号识别系统、脉冲编码器和对正传感器的位置反馈信号来确定的电机车的运行速度曲线。给出了该系统的硬件结构及软件流程图。本系统结构简单，实现方便，控制精度较高，并对恶劣环境有较强的适应能力。     

Changes in the body size of UK and US children over the past three decades

The major sources of published anthropometric data on children are now over two decades old. Due to concern being expressed regarding the continued validity of such data, changes in the body sizes of the UK child population over the past three decades have been considered. Comparisons were also made between the size of the current UK child population to the current US child population, and to the most comprehensive source of measured data on US children (but which are now over 20 years old). The growth of children in the UK and US over the past three decades was assessed for an indication of secular growth trends. Stature increases were found to have generally been less than body weight increases (as a percentage) at 5th percentile, mean and 95th percentile levels for UK children, and UK children were found to be closer in size to US children now than they were 30 years ago.     

Precision of the CAESAR scan-extracted measurements

Three-dimensional (3D) body scanners are increasingly used to derive 1D body dimensions from 3D whole body scans for instance, as input for clothing grading systems to make made-to-measure clothing or for width and depth dimensions of a seated workstation. In this study, the precision of the scanner-derived 1D dimensions from the CAESAR survey, a multinational anthropometric survey, was investigated. Two combinations of scanning teams with 3D whole body scanners were compared, one called the US Team and the other the Dutch Team. Twenty subjects were measured three times by one scanner and one team, and three times by the other combination. The subjects were marked prior to scanning using small dots, and the linear distances between the dots were calculated after processing the scans. The mean absolute difference (MAD) of the repetitions was calculated and this was compared to reported acceptable errors in manual measurements from the US Army's ANSUR survey when similar measurements were available. In addition, the coefficient of variation (CV) was calculated for all measurements. The results indicate that the CAESAR scan-extracted measurements are highly reproducible; for most measures the MAD is less than 5mm. In addition, more than 93% of the MAD values for CAESAR are significantly smaller than the ANSUR survey acceptable errors. Therefore, it is concluded that the type of scan-extracted measures used in CAESAR are as good as or better than comparable manual measurements. Scan-extracted measurements that do not use markers or are not straight-line distances are not represented here and additional studies would be needed to verify their precision.     

基于工作项目的《网络测试与监控技术》课程体系及其标准分析与研究

本文从网络的生命周期以及网络技术的三个层面出发,通过对从结构化布线技术、网络认证级的测试评估、全网网络故障诊断等网络技术方面和学生就业方面的调研和分析,阐述了基于工作项目的《网络测试与监控技术》课程设置的必要性并开发了课程标准。     

Task demands and human capabilities in door use

Doors are ubiquitous in the built environment, bur despite their frequent use by people and their involvement in over 300,000 injuries per year (USA), they are little studied from a human factors perspective. This paper provides a classification scheme for doors based on human/door interaction and a prototypical task analysis of door use. Two observational studies were performed on a particular type of door. The first observed 1600 human/door interactions and found that people's use of force-enhancing strategies increased for larger doors, particularly for people of smaller stature. The second observed 800 interactions with push doors and found that the pont where force is exerted is higher for taller individuals and closer to the center of the door than is typically assumed for placing handles. Th second study was partly corroborated by measuring the position of wear patterns on doors. As is expected in human factors, the was people used doors was a function of both task demands and human capabilities. These results suggests that those specifying doors for building s use a restoring torque below 30 Nm and site the handle or push plate 250-350 mm from the door edge and 1000-1500 mm above the floor.     

School furniture and the user population: an anthropometric perspective

The purpose of this study was to determine the relationship between reported spinal symptoms in an adolescent student population, and the match between their individual anthropometric dimensions and their school furniture. The hypothesis was that students who were too large or too small for their school furniture, i.e. with anthropometric measurements furthest from the group whose anthropometry was the ‘best fit’ with the furniture, would have a higher frequency of reported symptoms. From data collected from 1269 schoolchildren, reported spinal symptoms and anthropometric measures were examined. Stature measures were divided into quartiles. A standard government issue school chair and desk was measured and the anthropometric quartile of the population having the ‘best fit’ with the furniture was identified using standard ergonomics recommendations. Odds ratios were calculated for spinal symptoms reported within each quartile group. The first quartile group (the smallest students) was identified as having the ‘best fit’ with the school furniture. An overall higher odds of reporting low back pain was noted in students with anthropometric dimensions in the fourth quartile (the tallest students). While it is acknowledged that there is a multifactorial nature of causality of adolescent spinal symptoms, it is contended that the degree of mis-match between child anthropometry and school furniture set-up should be further examined as a strong and plausible associate of adolescent low back pain.     

Match between school furniture dimensions and children's anthropometry

The purpose of the study was to examine whether school furniture dimensions match children's anthropometry. Children aged 6-18 years (n=274), divided into 3 groups on the basis of the used furniture size, were subjected into anthropometric measurements (shoulder, elbow, knee and popliteal height, buttock-popliteal length and hip breadth). Combinational equations defined the acceptable furniture dimensions according to anthropometry and match percentages were computed, according to either the existing situation--where children use the size assigned for their grade--or assuming that they could use the most appropriate of the sizes available. Desk and seat height were bigger than the accepted limits for most children (81.8% and 71.5%, respectively), while seat depth was appropriate for only 38.7% of children. In conclusion, the assumption that children could use the most appropriate yet available size significantly improved the match, indicating that the limited provision of one size per cluster of grades does not accommodate the variability of anthropometry even among children of the same age.     

8B10B编解码器在PCI Express总线中的实现

本文在深入研究8B10B编、解码原理的基础上,利用其DWS特性,用Verilog HDL语言实现编、解码算法的描述,并通了modelsim仿真.在ISE9.1i平台上综合后下载到FPGA上实现具体的硬件电路,同时分析了系统各项性能.在PCI Express总线上,实现了一个性能良好的8810B编解码系统,它具有很好的可移植性以及一定的实用价值.     

Maximum reach envelope for the seated and standing male and female for industrial workstation design

Maximum reach envelopes for the 5th, 50th and 95th percentile reach lengths of males and females in seated and standing work positions were determined. The use of a computerized potentiometric measurement system permitted functional reach measurement in 15 min for each subject. The measurement system captured reach endpoints in a dynamic mode while the subjects were describing their maximum reach envelopes. An unbiased estimate of the true reach distances was made through a systematic computerized data averaging process. The maximum reach envelope for the standing position was significantly (p < 0.05) larger than the corresponding measure in the seated position for both the males and females. The average reach length of the female was 13.5% smaller than that for the corresponding male. Potential applications of this research include designs of industrial workstations, equipment, tools and products.     

Equations for defining the mismatch between students and school furniture: A systematic review

The present study reviews the scientific literature that describes the criteria equations for defining the mismatch between students and school furniture. This mismatch may negatively affect students' performance and comfort. Seventeen studies met the criteria of this review and twenty-one equations to test six furniture dimensions were identified. There was substantial mismatch between the relative heights of chairs and tables. Some systematic errors have been found during the application of the different equations, such as the assumption that students are sitting on chairs with a proper seat height. Only one study considered the cumulative fit. Finally, some equations are based on contradictory criteria and need to develop and evaluate new equations for these cases.Relevance to industryUltimately, the present work is a contribution toward improving the evaluation of school furniture and could be used to design ergonomic-oriented classroom furniture.     

Evidence for the need to update the Chilean standard for school furniture dimension specifications

Some countries decide to use standards to define the type of furniture dimensions that should be used according to students' anthropometric characteristics. The aim of this paper is to generate data to update the standard for Chilean school furniture using student anthropometric data. The sample used involved 3078 students. Data collection included eight anthropometric dimensions. A strict procedure was followed to define six furniture school dimensions. The definition of the compatibility between students' characteristics and furniture dimensions was done using the concept of mismatch computed through a set of equations. The results showed differences in mismatch levels between the two compared approaches, with lower mismatch found using the new proposed approach – the updated standard (UpS). Seat depth presents the greatest difference in mismatch, with values of 43% for the current Chilean standard (ChS) and 17% for the UpS. Also, seat height match values are almost the same (100%); however, it is important to mention that the level of match could drop to 82% in the ChS if the furniture selection was already carried out, as suggested in the standard itself, by using the Stature. Finally the UpS presents a higher covered range in the six furniture dimensions. The obtained results reflect the need to update the data and the procedure for school furniture selection presented by the current Chilean standard. Relevance for industry: this paper presents relevant data to be used by both school furniture designers, as well as by those responsible for the furniture selection at schools. In addition, proof is presented that school furniture standards need to be updated periodically in order to better fit the students’ anthropometric characteristics.     

Anthropometry of the Singaporean and Indonesian populations

This research collected anthropometric data of the Singaporean and Indonesian populations. The data were mainly from university students. In total, 245 male and 132 female subjects from Indonesia and 206 male and 109 female subjects from Singapore were measured. The Singapore data were divided into three sub-groups, comprising Singapore overall, Singapore citizens, and the Chinese ethnic sub-group. The Indonesians data were divided into two sub-groups, comprising Indonesia citizens and Indonesia Chinese. This study used 36 measurement dimensions. The authors made a comparison with previous anthropometric data collected in 1990 of over a thousand Singaporeans.The main contributions of this study are: i) an updated anthropometric database of Singaporeans and Indonesians, ii) a comparison of the two samples obtained, and iii) a projection of dimensional changes over time from comparing past to more recent anthropometric data. Statistical analyses show that Singaporeans (both male and female) tend to have larger dimensions than Indonesians in general. In addition, the data reveal the current sample to be significantly larger on more than 50 percent of the dimensions measured, for both males and females.In providing instances of possible application, the Body Mass Index (BMI) of all sub-groups was calculated. The results show both samples to have normal indexes with BMIs in the range of 18.5–25.0. This paper presents also an empirical estimation of unknown anthropometric characteristics using the Ratio Scaling Method. The purpose is to estimate uncollected anthropometric data based on a given scaling dimension. Overall, the reported anthropometric data and analyses can be used as relevant consideration in product and systems design.

Relevance to industry

The findings of this study indicate differences between Singaporean and Indonesian anthropometry in the citizen and Chinese sub-groups. The utilization of an updated anthropometric database that incorporates geographical origin and ethnic group is useful. Product designers would be able to cater to a wider range of target users.     

Reach distance and safety standards

The reach of British males of 99th percentile stature over different height barriers was determined to establish reach distances for a proposed Comite Europeen de Normalisation (CEN) standard. The distances recorded are considerably in excess of those given in the draft West German standard DIN 310011984, and those given in the recently published British standard code of practice for safety of machinery BS.5304. Data are included from earlier experiments which show that the safety distances would also be inadequate for the 95th percentile stature British male. It is suggested that reasons for the discrepancies arise mainly from the differences in the way that the reach measurements were obtained.     

地铁折返站行车能力的分析与研究

针对在运地铁线路行车能力不足的现象,分析了行车能力的计算模型.线路行车能力的薄弱环节在于折返站的行车能力.研究折返站的行车能力重点在于研究行车间隔.车站的配线方式决定了不同的折返方式.而不同折返方式可分解为不同的折返流程.所有流程中,行车间隔最大的环节决定了折返站的行车能力.详细分析了各种折返流程的行车间隔.结合广州地...