Design of genetic-fuzzy control strategy for parallel hybrid electric vehicles

Hybrid Electric Vehicles (HEVs) generate the power required to drive the vehicle via a combination of internal combustion engines and electric generators. To make HEVs as efficient as possible, proper management of the different energy elements is essential. This task is performed using the HEV control strategy. The HEV control strategy is the algorithm according to which energy is produced, used and saved. This paper describes a genetic-fuzzy control strategy for parallel HEVs. The genetic-fuzzy control strategy is a fuzzy logic controller that is tuned by a genetic algorithm. The objective is to minimize fuel consumption and emissions, while enhancing or maintaining the driving performance characteristics of the vehicle. The tuning process is performed over three different driving cycles including NEDC, FTP and TEH-CAR. Results from the computer simulation demonstrate the effectiveness of this approach in reducing fuel consumption and emissions without sacrificing vehicle performance.     

Real-time energy optimization of HEVs under-connected environment: a benchmark problem and receding horizon-based solution

In this paper, we propose a benchmark problem for the challengers aiming to energy efficiency control of hybrid electric vehicles (HEVs) on a road with slope. Moreover, it is assumed that the targeted HEVs are in the connected environment with the obtainment of real-time information of vehicle-to-everything (V2X), including geographic information, vehicle-toinfrastructure (V2I) information and vehicle-to-vehicle (V2V) information. The provided simulator consists of an industriallevel HEV model and a traffic scenario database obtained through a commercial traffic simulator, where the running route is generated based on real-world data with slope and intersection position. The benchmark problem to be solved is the HEVs powertrain control using traffic information to fulfill fuel economy improvement while satisfying the constraints of driving safety and travel time. To show the HEV powertrain characteristics, a case study is given with the speed planning and energy management strategy.     

基于二次型性能指标的混合动力汽车实时优化控制

为解决混合动力系统实时优化控制问题,本文提出了一种基于二次型性能指标最优的混合动力汽车功率分配优化方案.通过合理的假设和近似,建立了混合动力系统的线性模型,并利用二次型最优控制理论将混合动力最优控制问题转化为二次型最优调节问题进行求解,得到了一个结构简单的实时优化控制算法.5种道路工况下的仿真结果表明,本文提出的控制方法在未来道路工况未知的情况下能够实现混合动力系统的实时优化控制,且节油率与离线计算以燃油消耗最小为性能指标的全局最优控制的节油率相近.     

Risk assessments of work-related musculoskeletal disorders among the TFT-LCD manufacturing operators

The thin film transistor liquid crystal display (TFT-LCD) industry is one of the major industries in Taiwan, yet few studies addressed its work-related musculoskeletal disorders (WMSDs). Thus, this study aims to evaluate the risk of WMSDs among the operators of a TFT-LCD manufacturing company in Taiwan by using the subjective questionnaire and ergonomic assessment tools. First, the NMQ survey was conducted among 393 operators, accounting for 94% of all operators in the TFT-LCD plant. The results showed that the prevalence of WMSDs was 31.8%. Among the various body parts, the highest prevalence of WMSDs was found in neck and shoulders (20.4%), while upper limbs were with the lowest prevalence (9.2%). Besides, the prevalence of WMSDs tends to be affected by both work factors and operator factors. Those who were more experienced, working in day shift and involved in the Array process tend to have a higher prevalence of WMSDs. Further, female and domestic operators reported a higher prevalence of WMSDs than male and foreign operators. Moreover, the jobs of 50 employees were analyzed using ergonomic assessment tools including OSHA MSDs, BRIEF, OWAS, 3D SSPP, and NIOSH lifting equation. The findings indicated that inadequate working height, restricted working space, awkward postures, overweight load, and high repetition were the major risk factors of WMSDs. Thus, countermeasures such as redesigning the workstations and material handling carts, proactive training of manual material handling, and providing safety clearance are recommended to enhance the occupational health and safety of the TFT-LCD operators.     

A review of: “Catastrophic Failures”. By V. BIGNELL,G. PETERS and C. PYM. (Milton Keynes: OPEN UNIVERSITY PRESS, 1977.) [Pp.274.] £5·50.

Cumulative trauma illness currently accounts for over half of all occupational illness in the United States. From 1987 to 1989 there was a 100% increase in the reported number of cases of cumulative trauma illness (Bureau of Labor Statistics 1990). Shoulder region pain ranks second only to low back and neck pain in clinical frequency, and the occurrence of occupational shoulder illness is on the rise. This paper summarizes findings of a subset of recent epidemiologic, laboratory, and field studies conducted in order to identify occupational risk factors for cumulative trauma disorders (CTDs) of the shoulder region. These studies have identified the following risk factors as being associated with particular shoulder pain syndromes: awkward or static postures, heavy work, direct load bearing, repetitive arm movements, working with hands above shoulder height, and lack of rest. The paper begins with a discussion of several shoulder disorders, includes problems in studying cumulative trauma, presents results of recent studies, and concludes with suggested ergonomic controls that could help to reduce the incidence of shoulder disorders, by eliminating or reducing exposure to the associated risk factors.     

混合动力系统能量管理策略的实时优化控制算法

依据最优控制理论得到的混合动力汽车能量管理策略与未来的驾驶需求相关联,无法解决算法的实时性问题.本文另辟蹊径,结合规则构造二次型性能指标来限制发动机功率的大幅度频繁波动,间接地降低油耗.为此,在对混合动力系统近似线性处理的基础上,利用二次型最优跟踪理论推导出定常的反馈控制律,将发动机和电机功率表示成系统当前状态和车速指令的线性函数并应用于非线性实车系统.仿真结果表明,本文提出的能量管理实时控制算法可以达到良好的节油效果, 对不同的道路工况和电池初始荷电状态有良好的适应性.     

Association of Risk Factors with Musculoskeletal Disorders among Male Commercial Bus Drivers in Malaysia

A national study in Malaysia was conducted with the main objective being to determine the prevalence of musculoskeletal disorders (MSDs) and the association between risk factors and MSDs among Malaysian bus drivers. Cross‐sectional data were collected from 1,181 male commercial bus drivers in Malaysia using questionnaires to determine demographic, working characteristics and a translated Nordic questionnaire to determine MSD complaints. A Human Vibration Meter was used to measure whole body vibration (WBV) exposure, and postural analysis was used to evaluate awkward working posture. To assess psychological factors, the validated Profile of Mood States (POMS) was used. The overall prevalence of MSD was 81.8% and, by body parts, low back pain was reported to be the highest complaint of lifetime MSD (58.5%) compared to other body parts. The levels of WBV acceleration magnitude A(8) exceed the European Union Directive (0.54 m/s² root‐mean‐square [r.m.s.] acceleration), and only 1.2% of the bus drivers adopt more than 40% of awkward postures while driving. Logistic regression analysis, controlling for age, income, education level, and work activities, revealed that factors such as lack of seat adjustability, uncomfortable seat, seat's material, seat contour and design, WBV exposure, smoking, frequency of daily trips, duration of daily driving, prolonged sitting, working part time, and psychological factors (namely, feeling stress, feeling worried, feeling fatigued) were important risk factors of MSDs among Malaysian bus drivers. As a conclusion, bus drivers are exposed to a combination of risk factors that may lead to an increased risk of developing MSDs. © 2012 Wiley Periodicals, Inc.     

Musculoskeletal disorders among male sewing machine operators in shoemaking

Research on the relationship between the operation of sewing machines and the appearance of musculoskeletal disorders has been conducted mainly among women working in garment or textile production, in developed countries; little is known about male sewing machine operators in other industries, in less developed countries. This study involved 143 Mexican men operating sewing machines in eight shoe factories; 132 of them operated flat-type machines, 11 column-type machines. When studied, the operators had been in this task for at least one year. The study aimed to identify the body regions more liable to develop musculoskeletal disorders and the rates both of appearance of such troubles and of sick leave resulting from them. A questionnaire was given to each worker, asking for their work history, the presence of musculoskeletal disorders at the time of the inquiry, and the frequency of sick leave during the previous 12 months; additionally, a number of workers were filmed on video and this material was then used to identify the body regions undergoing the major work demands. 47·5% of the subjects declared current musculoskeletal disorders; a statistical difference was found when the two groups were considered separately. Low back pain was the most frequent at a rate of 18·2% for both groups; the shoulder was a site of complaint for 14% of the subjects, being three times more frequent among column-machine operators; the back as a whole was mentioned also by 14% of the subjects, all of them flat-machine operators; 4·9% of the subjects complained of neck pain and again none of the column-machine operators was affected. Only one subject had taken sick leave because of musculoskeletal problems. The body regions affected were those expected from the analysis of the video recordings and were consistent with those reported for occupations involving similar postures and movements. The rates of musculoskeletal complaint found in this study are lower than those reported by other authors who have studied sewing machine operators; taking sick leave is a very rare choice for the workers studied.     

Associations of ergonomic and psychosocial work hazards with musculoskeletal disorders of specific body parts: A study of general employees in Taiwan

Background and aimsMusculoskeletal disorders (MSDs) are major occupational health concerns. This study examined the associations of ergonomic and psychosocial work hazards with the risks of MSDs of specific body parts and their distribution across a wide range of occupational groups.MethodsStudy participants comprised 8,937 male and 7,052 female employees aged 20–65 years from a nationwide survey in 2016. A self-report questionnaire was administered to obtain information regarding demographic characteristics, work conditions, ergonomic and psychosocial work hazards, and MSDs of different body parts in 12 months. Multivariate logistic regression models were used to estimate prevalence ratios of MSDs in relation to ergonomic and psychosocial work hazards.ResultsIn professionals and skilled workers, MSDs of the neck and shoulders were more prevalent, whereas in manual workers, MSDs of the hands, wrists, and lower back were more prevalent. Psychosocial work hazards, including high psychological demand and low workplace justice, were major work-related risk factors for shoulder and neck disorders, whereas ergonomic hazards were major work-related risk factors for lower back and wrist or hand disorders.ConclusionDifferent workplace hazards contribute to the risks of different MSDs. To prevent the development of MSDs, occupational health professionals should evaluate both ergonomic and psychosocial work hazards and develop health prevention programs tailored to the risk profiles of working populations.     

Working hours as a risk factor in the development of musculoskeletal complaints

The length of daily working hours as a risk factor for the development of musculoskeletal complaints was studied by comparing the sick leave statistics of 408 sewing machine operators on full-time schedules (8 h working day) with 210 operators on part-time schedules (5 h working day). Working part-time was shown to postpone the occurrence of sick leave due to musculoskeletal disorders by approximately half a year. There was no lasting effect on the reduction in working hours on sick leave due to shoulder-neck complaints, but a reduction in low back complaints was indicated. It is suggested that any reorganization of work activities to counteract musculoskeletal injuries from repetitive work should aim to break up the muscular activity patterns over time periods considerably shorter than the 5 h working day of the part-time workers in the present study.     

Assessment of Risk of Musculoskeletal Disorders among Crane Operators in a Steel Plant: A Data Mining–Based Analysis

Prevalence of musculoskeletal disorders (MSD) among industrial workers is often measured through the Nordic Musculoskeletal Questionnaire (NMQ) survey that captures the MSD complaints across different body parts. The outcomes of such a survey are reported in terms of relative frequency of MSD complaints for the body parts affected and are analyzed through t test, analysis of variance, or logistic regression. The study augments the analysis of NMQ data using relative risk, a statistical measure of prevalence, and classification and regression tree (CART), a data mining–based decision tree. The integrated analysis is done for 76 crane operators of a steel plant in India that considers operators, task, and workplace characteristics as predictors of MSD. The relative risk indices for each of the predictor categories compare the risk of prevalence of MSD. The outcomes of CART‐based analysis are objective importance scores that quantify the contributions of the predictors toward the occurrence and severity of MSD. A risk priority index is computed to prioritize the predictor variables with categories in terms of their contribution. The study shows that the lower back and neck and shoulder are the most affected and account for 78.75% of the MSD complaints. CART shows that crane height contributes the maximum for MSD occurrences of both lower back and neck and shoulder. However, for MSD severity, while crane height contributes the most for neck and shoulder, cabin feature (static or movable) contributes the maximum for the lower back.     

The investigation of work-related musculoskeletal disorders among female workers in a hazelnut factory: Prevalence,working posture,work-related and psychosocial factors

BackgroundWork-related musculoskeletal disorders (WMSDs) are the most common occupational health problems in the industrialized world. The identification of WMSDs specific to occupation is essential to plan and implement preventative programs. This study investigated the prevalence of WMSDs and determined the factors related to the severity of the most common disorders among female workers in a hazelnut factory.MethodsA total of 114 female workers were examined in this cross-sectional study using the Nordic Musculoskeletal Questionnaire, the Dutch Musculoskeletal Questionnaire, and an author-developed questionnaire (for socio-demographic characteristics and psychosocial factors). Working posture, craniovertebral angle, thoracic kyphosis angle (TKA), and lumbar lordosis angle were evaluated based on a photogrammetry method using the ImageJ program.ResultsThe prevalence of WMSDs in at least one body part during the last 12 months was 92.1%. The highest prevalence of WMSDs was in the lower back (61.4%), neck (57.9%), shoulder (53.6%), and upper back (45.6%). The least affected part was the elbow. Lower back, shoulder, and neck disorders were the most common causes of activity limitation. The severity of lower back pain was associated with stress in the workplace and work-related factors. The neck pain severity was related to craniovertebral angle and work-related factors. The shoulder pain severity increased with TKA and employment duration. TKA was related to upper back pain severity.ConclusionsWMSDs are common among female workers in a hazelnut factory. Reorganizing of working posture, work-related factors, and stress at work may be beneficial to decrease the prevalence of WMSDs and pain severity.Relevance to Industry; The female workers in the hazelnut factory are vulnerable to the work-related musculoskeletal disorders, particularly in the spinal region. The employers should endeavor to improve the health of the workers by the adjustment of the working posture and environmental factors.     

An epidemiological study of low-back pain in crane operators

Abstract

A survey among workers in a steel factory was conducted to determine the risk for low-back pain (LBP) among male crane operators. Crane operators (n = 33) were matched for age with male control workers (n = 30)p and examined for frequency and nature of LBP by the on-site medical service. Comparison between crane operators and controls showed a statistically significant odds ratio for LBP of 3-6. Although crane operators had been exposed more often to backstraining factors in previous occupations, in the employed logistic analysis only their current job explained the elevated occurrence of LBP. It is suggested that workers in sedentary position with exposure to whole-body vibration are at special risk for LBP. The results of this study provide evidence to strongly recommend persons with a history of back complaints not to seek employment as crane operators.     

Occupational musculoskeletal disorders in the neck and upper limbs of forestry workers exposed to hand-arm vibration.

An epidemiologic and clinical study of neck and upper limb musculoskeletal disorders was carried out on 65 vibration-exposed forestry operators using chain-saws and 31 comparable control subjects (maintenance workers) performing manual activity and not exposed to vibration. Upper limb function was evaluated by measuring finger and wrist circumference size, maximal hand grip strength and range of motion manoeuvres in both the controls and the exposed workers. Vibration from two chain-saws was measured, and vibration exposure for each forestry worker was assessed in terms of 4 h energy-equivalent frequency-weighted acceleration according to ISO 5349. Job analysis indicated a slight excess risk of upper extremity cumulative trauma disorders (CTDs) in the forestry operators compared with the control workers. After adjustment for age and body constitution, significantly higher prevalence rates of persistent upper limb pain, muscle-tendon syndromes and carpal tunnel syndrome were observed among the forestry workers than among the controls. In the forestry operators, the occurrence of upper limb musculoskeletal disorders increased with increasing vibration exposure. Upper limb function was found to be impaired in the forestry workers compared with the controls. Vibration exposure was significantly related to increased finger circumference size, diminished muscle force and reduced joint function. Even though it is difficult to establish the relative importance of vibration and ergonomic factors in the aetiology of CTDs, nevertheless the results of this study indicate that musculoskeletal impairment to the upper limbs was more severe in the forestry operators than in the controls who did solely manual work. This finding and the observed dose-effect relationships suggest that vibration stress is an important contributor to the development of musculoskeletal disorders in workers using hand-held vibrating tools.     

The prevalence of neck pain and associated risk factors among undergraduate students: A large-scale cross-sectional study

BackgroundNeck pain is a pervasive ailment causing work absenteeism, disabilities, and sleep disturbance among working adults. While the onset of neck pain in many individuals may date back to college-age, little is known regarding the prevalence of neck pain and associated risk factors among undergraduates. The current study aimed to compare the prevalence of neck pain among students in different undergraduate programs and to investigate their risk factors.MethodsUndergraduates from two universities were invited to participate in a self-administered online survey. The survey collected data regarding demographics, previous and the current neck pain symptoms, and potential risk factors (e.g., gender, age, body mass index, study programs, electronic devices usage, study hours, sports participation, and anxiety and depression levels, etc.). Multiple logistic regressions were conducted to identify risk factors for neck pain.ResultsA total of 5,195 invitation emails were sent. Of 1,002 respondents, 22.3% reported having current neck pain. Physiotherapy (26.5%) and nursing students (26.1%) had significantly higher prevalence of neck pain as compared to business students (13.2%). Anxiety (odds ratio (OR):1.11, 95%CI:1.07–1.16), concurrent low back pain (OR:3.28, 95%CI:2.15–5.00) and senior years of studies (OR:1.19,95%CI:1.01–1.41) were significantly associated with the presence of neck pain. Taller students (OR:1.02,95%CI:0.99–1.05) and prolonged smartphone usage (OR:1.05,95%CI:0.99–1.12) appeared to be associated with the presence of neck pain.ConclusionThis study not only revealed the high prevalence of neck pain among undergraduates but also identified several modifiable and non-modifiable risk factors for neck pain in this population. Specific prevention strategies should be developed and implemented to reduce the risk of neck pain in vulnerable students.     

Measurement of whole‐body vibration exposure from unsuspended cabin tractor semi‐trailers

Indian tractor semi‐trailer drivers are exposed to mechanical whole‐body vibration during their work. Some drivers suffer from low‐back pain from this vibration. However, there is no evidence of a relationship between the whole‐body vibration from tractor semi‐trailers and low‐back pain or occupational disease because of the lack of investigations. A field study was conducted to characterize the health risks associated with driving tractor semi‐trailers. Studies were conducted at different loadings and on different road surfaces as well as at different speeds, with the vibrations measured at the driver–seat interface on x‐longitudinal, y‐transverse and z‐vertical axes. The vibrations were compared with the health‐risk guidance according to Annex B of ISO 2631‐1 (ISO 2631/1, 1997). The findings of this study indicated that Indian tractor semi‐trailer drivers should not operate continuously more than 4 h a day under current working conditions. © 2011 Wiley Periodicals, Inc.     

Work posture,working conditions and musculoskeletal outcomes in agricultural workers

This study evaluated the working postures, working conditions and musculoskeletal outcomes among different agricultural workers in Iran. Data were collected using questionnaires and direct observations of posture (using the Rapid Upper Limb Assessment [RULA] method) from 377 farmers including 150 rice farmers, 122 vegetable growers, and 105 greenhouse workers. The overall prevalence of musculoskeletal symptoms, particularly in the low back (75.1%), knees (62.1%), upper back (61.55%), and neck (59.9%) was very high, and 72.6% of farmers experienced more than three locations of pain/discomfort. The mean RULA grand score of 6.7 highlighted that most farmers needed immediate investigation and changes in their working postures. Being female (neck pain), occupation (rice farmers – low back pain), number of years worked as an agricultural worker (neck and knee pain), prolonged daily working hours (upper back pain), job satisfaction (neck and low back pain), fast working (upper back pain), and working postures (neck, upper back, low back and knee pain) were independently associated with the presence of musculoskeletal symptoms. These findings emphasise the need for multiple component interventions to improve the working conditions of this population.     

Vibrations transmitted from human hands to upper arm,shoulder, back,neck, and head

Some powered hand tools can generate significant vibration at frequencies below 25 Hz. It is not clear whether such vibration can be effectively transmitted to the upper arm, shoulder, neck, and head and cause adverse effects in these substructures. The objective of this study is to investigate the vibration transmission from the human hands to these substructures. Eight human subjects participated in the experiment, which was conducted on a 1-D vibration test system. Unlike many vibration transmission studies, both the right and left hand-arm systems were simultaneously exposed to the vibration to simulate a working posture in the experiment. A laser vibrometer and three accelerometers were used to measure the vibration transmitted to the substructures. The apparent mass at the palm of each hand was also measured to help in understanding the transmitted vibration and biodynamic response. This study found that the upper arm resonance frequency was 7–12 Hz, the shoulder resonance was 7–9 Hz, and the back and neck resonances were 6–7 Hz. The responses were affected by the hand-arm posture, applied hand force, and vibration magnitude. The transmissibility measured on the upper arm had a trend similar to that of the apparent mass measured at the palm in their major resonant frequency ranges. The implications of the results are discussed.Relevance to industryMusculoskeletal disorders (MSDs) of the shoulder and neck are important issues among many workers. Many of these workers use heavy-duty powered hand tools. The combined mechanical loads and vibration exposures are among the major factors contributing to the development of MSDs. The vibration characteristics of the body segments examined in this study can be used to help understand MSDs and to help develop more effective intervention methods.     

Perceived musculoskeletal symptoms among dental students in the clinic work environment

Musculoskeletal symptoms are a major concern among dental practitioners. Dental students perform the same clinical tasks as dentists in private practice, yet only recently has scientific evidence suggested a relationship between the tasks and musculoskeletal symptoms. This study investigates the clinical tasks that place students at physical risk and the relationship between the tasks and musculoskeletal symptoms. Student perceptions of physical symptoms were established with a questionnaire identifying variables on general health, tasks, physical demands, workload and environment. A total of 61% (358/590) reported that during the past year they experienced musculoskeletal symptoms related to work at dental school (second year (n = 212), third year (n = 201) and fourth year (n = 177)). Of those students, the neck represented 48%, shoulder 31%, back 44% and hands 20% (p < 0.001). Third year students reported the highest occurrence of symptoms in every body area (p < 0.001). Third and fourth year students reported significant relationships between the occurrence of symptoms and equipment utilisation, work efficiency and general health. Further studies are recommended to evaluate types and levels of potential risk factors. A total of 75% of dental practitioners are at risk for developing work-related musculoskeletal disorders. Results from this study have found that dental students were no exception. Third year dental students reported the highest level of musculoskeletal symptoms with the prevalence of pain in the neck, shoulder and lower back.     

Ergonomic,job task,and psychosocial risk factors for work‐related musculoskeletal disorders among teleservice center representatives

A cross‐sectional study was conducted to evaluate the association between work‐related musculoskeletal disorders (WRMDs) and work conditions, perceived exhaustion, job dissatisfaction, and job‐stress issues at two teleservice centers (TSCs). The study covered teleservice representatives who respond to toll‐free calls for assistance. The work involves a computer or manual search for information, and data entry using keyboards. One facility had upgraded the furniture at the workstations; the other facility had not. A questionnaire survey among 114 teleservice representatives and an ergonomic evaluation were conducted to determine WRMDs and their risk factors and perceived job stress. A high prevalence of symptoms of WRMDs was found at both TSCs. Suboptimal ergonomic conditions were associated with neck, shoulder, elbow, and back WRMDs, as well as with increased job dissatisfaction. Perceived increased workload variability and lack of job control were associated with the occurrence of neck and back WRMDs, respectively. WRMDs were more frequently reported by teleservice representatives at the center with older furniture and suboptimal ergonomic conditions. WRMDs may be prevented by improving ergonomic conditions at workstations and addressing work‐organization elements.