Seat belt use and fit among drivers aged 75 years and older in their own vehicles

Objective: This article aims to describe seat belt wearing patterns and quality of seat belt fit among drivers aged 75 years and older. A secondary aim is to explore associations between body shape, comfort, and seat belt use patterns.

Methods: This is an observation and survey study of a cohort of 380 drivers aged 75 years and over. During home visits, photographs were taken of the drivers in their vehicles for later analysis of belt fit and a short survey was also administered to collect demographic data and information about seat belt use and comfort. Seat belt fit and use of belt and seat accessories were analyzed from the photographs.

Results: Data from 367 participants with photographs were analyzed. Whereas 97% reported using a seat belt and 90% reported their seat belt to be comfortable, 21% reported repositioning their seat belt to improve comfort. Good sash and lap belt fit were achieved in 53 and 59% of participants, respectively, but only 35% achieved overall good fit. Both poor sash and lap belt fit were observed in 23% of participants. Drivers who were in the obese category had over twice the odds (95% confidence interval [CI], 1.2–4.1) of having a poor lap belt fit than those in the normal body mass index [BMI] range, and drivers who were overweight had 1.8 times the odds (95% CI, 1.1–2.9) of having poor lap belt fit. Older females also had twice the odds (95% CI, 1.3–3.5) of poor lap belt fit compared to older males, regardless of BMI. Sash belt fit did not vary significantly by BMI, stature, or gender. However older drivers who reported that they had not made any adjustments to the D-ring height had 1.7 times the odds of having poor sash belt fit than those who made adjustments (1.2–2.9). Females were 7.3 times more likely to report comfort problems than males (95% CI, 3.2, 16.3) but there was no association between reported comfort and BMI or seat belt fit. Drivers who reported comfort problems had 6 times the odds (3.2–13.6) of also reporting active repositioning of the belt.

Conclusions: The results suggest that older drivers face challenges in achieving comfortable and correct seat belt fit. This may have a negative impact on crash protection. Belt fit problems appear to be associated with body shape, particularly high BMI and gender. There is a need for further investigation of comfort accessories; in the interim, older drivers and occupants should be encouraged to use features such as D-ring adjusters to improve sash belt fit.     

Children's and Adults’ Comfort Experience of Extra Seat Belts When Riding in the Rear Seat of a Passenger Car

Objective: The objective of this study was to explore passengers’ comfort experience of extra seat belts during on-road driving in the rear seat of a passenger car and to investigate how the use of extra belts affects children's and adults’ attitudes to the product.

Methods: Two different seat belt systems were tested, criss-cross (CC) and backpack (BP), consisting of the standard 3-point belt together with an additional 2-point belt. In total, 32 participants (15 children aged 6–10, 6 youths aged 11–15, and 11 adults aged 20–79, who differed considerably in size, shape, and proportions) traveled for one hour with each system, including city traffic and highway driving. Four video cameras monitored the test subject during the drive. Subjective data regarding emotions and perceived discomfort were collected in questionnaires every 20 min. A semistructured interview was held afterwards.

Results: All participant groups accepted the new products and especially the increased feeling of safety (P <.01); 56% preferred CC and 44% preferred BP but the difference was not significant. In total, 81% wanted to have extra seat belts in their family car. CC was appreciated for its symmetry, comfort, and the perceived feeling of safety. Some participants found CC unpleasant because the belts tended to slip close to the neck, described as a strangling feeling. BP was simpler to use and did not cause annoyance to the neck in the way CC did. Instead, it felt asymmetric and to some extent less safe than CC. Body size and shape affected seat belt fit to a great extent, which in turn affected the experience of comfort, both initially and over time. Perceived safety benefit and experienced comfort were the most determinant factors for the attitude toward the extra seat belts. The extra seat belts were perceived as being better than the participants had expected before the test, and they became more used to them over time.

Conclusion: This exploratory study provided valuable knowledge from a user perspective for further development of new seat belt systems in cars. In addition to an increased feeling of safety, seat belt fit and comfort are supplementary influencing factors when it comes to gaining acceptance of new seat belt systems.     

Low Back Muscle Activity in an Automobile Seat with a Lumbar Massage System

This investigation was conducted to determine the effects of a massaging lumbar support system on low back muscle activity. The apparatus included a luxury-level automobile seat, six 10-mm diameter bipolar surface electrodes, an amplifier, an analog-to-digital conversion board, data acquisition software, and a personal computer. Six experimental conditions, each involving a variation of massage time, were considered. The dependent variable was the change in the root mean square variation of the EMG signal. One minute of lumbar massage every 5 min was found to have a beneficial effect on low back muscle activity (as compared to no massage). This may prove to be an extremely important result in the quest to combat low back pain attributable to automobile seating.     

Flicker Test as a Load Measurement During the Combined Effect of Heat and Noise

This study was a joint physiological and psychological experiment undertaken to determine changes in physiological and psychological human functions under the combined influence of heat, noise, and physical activity. Seven experimental situations were simulated in a climatic chamber with different configurations of three independent variables: heat (40 °C), noise (98 dB), and physical effort (30% of maximum volume of oxygen uptake—V0₂ max). Five psychological variables (critical flicker fusion—CFF, hand tremor, reaction time, subjective climate evaluation, and subjective evaluation of the given condition load) and two physiological variables (heart rate and rectal temperature) were monitored. Results indicate that CFF changed (increased) significantly when more than one experimental variable was applied. These changes coincided with significant changes in both subjective climate evaluation and subjective evaluation of a given condition load. There were no significant changes in psychomotor functions (hand tremor and reaction time). None of the observed physiological parameters were above the critical value. The results suggest that CFF can be treated as a psychophysical load indicator.     

Workstation design in carpet hand-weaving operation: guidelines for prevention of musculoskeletal disorders.

Carpet weavers suffer from musculoskeletal problems mainly attributed to poor working postures. Their posture is mostly constrained by the design of workstations. This study was conducted to investigate the effects of 2 design parameters (weaving height and seat type) on postural variables and subjective experience, and to develop guidelines for workstation adjustments. At an experimental workstation, 30 professional weavers worked in 9 different conditions. Working posture and weavers' perceptions were measured. It was shown that head, neck and shoulder postures were influenced by weaving height. Both design parameters influenced trunk and elbows postures. The determinant factor for weavers' perception on the neck, shoulders and elbows was found to be weaving height, and on the back and knees it was seat type. Based on the results, the following guidelines were developed: (a) weaving height should be adjusted to 20 cm above elbow height; (b) a 10 degrees forward-sloping high seat is to be used at weaving workstations.     

Influence of seat properties on occupant dynamics in severe rear crashes

Seat performance in retaining an occupant, transferring energy, and controlling neck responses is often questioned after severe rear crashes when fatal or disabling injury occur. It is argued that a stiffer seat would have improved occupant kinematics. However, there are many factors in occupant interactions with the seat. This study evaluates four different seat types in 26 and 32 mph (42 and 51 km/h), rear crash delta Vs. Two seats were yielding with k = 20 kN/m occupant load per displacement. One represented a 1970s yielding seat with j = 3.4 degrees /kN frame rotation per occupant load, and 3 kN maximum load (660 Nm moment), and the other a high retention seat phased into production since 1997 with j = 1.4 degrees /kN, and 10 kN maximum load (2200 Nm). Two seats were stiff with k = 40 kN/m. One represented a 1990s foreign benchmark with j = 1.8 degrees /kN and a 7.7 kN maximum load (1700 Nm), and the other an all belts to seat (ABTS) with j = 1.0 degrees /kN and 20 kN maximum load (4400 Nm). The crash was a constant acceleration of 11.8 g, or 14.5 g for 100 ms. Occupant interactions with the seat were modeled using a torso mass, flexible neck and head mass. By analysis of the equations of motion, the initial change in seatback angle (Deltatheta) is proportional to jk(y - x), the product jk and the differential motion between the vehicle (seat cushion) and occupant. The transition from 1970s-80s yielding seats to stronger seats of the 1990s involved an increase in k stiffness; however, the jk property did not change as frame structures became stronger. The yielding seats of the 1970s had jk = 68 degrees /m, while the stiff foreign benchmark seat had jk = 72 degrees /m. The foreign benchmark rotated about the same as the 1970s seat up to 50 ms in the severe rear crashes. While it was substantially stronger, it produced higher loads on the occupant, and the higher loads increased seatback rotations and neck responses. The ABTS seat had the lowest rotations but also caused high neck responses because of the greater loads on the torso. Neck displacement (d) is initially proportional to (k/m(T)) integral integral y, seat stiffness times the second integral of vehicle displacement divided by torso mass. As seat stiffness increases, head-torso acceleration, velocity, and neck displacement increase. This study shows that the jk seat property determines the initial seatback rotation in rear crashes. If a stronger seat has a higher stiffness, it rotates at higher loads on the occupant, reducing the overall benefit of the stronger frame, while increasing neck responses related to whiplash or neck extension prior to subsequent impacts. The aim of seat designs should be to reduce jk, provide pocketing of the pelvis, and give head-neck support for the best protection in severe rear crashes. For low-speed crashes, a low k is important to reduce early neck responses related to whiplash.     

Perceived Discomfort and Electromyographic Activity of the Upper Trapezius While Working at a VDT Station

Ten female participants performed work at a video display terminal (VDT) station over a whole working day. Subjective local muscular fatigue was evaluated by means of the Category Ratio 10 scale. Electromyographic activity of the upper right and left trapezius was measured. A comparison was made between 5 participants who had previous complaints and 5 participants who reported no musculoskeletal problems in the shoulder-neck region. The subjective scores for the shoulder differed significantly between the two groups, being higher for the group with complaints. Both groups showed a decrease in discomfort after the lunch break. The activity of the trapezius increased significantly for both groups, in a more pronounced way for the group with disorders. Although it is found in literature that VDT work is a task with very low static loads, it seems from this study that the EMG activity increase can be an indication of muscle fatigue: More effort was required to accomplish the same VDT task at the end of the day.     

Upper limb load as a function of repetitive task parameters: part 2--an experimental study.

The aim of the study was to compare the theoretical indicator of upper limb load with the physiological indicator of musculoskeletal load, which is present while performing a repetitive task (a normalized electromyography [EMG] amplitude recorded from the muscles of the upper limb involved in the performed task). In an experimental study of a repetitive task, the EMG signal from 5 main muscles of the shoulder girdle, arm and forearm was registered: extensor carpi radialis longus, flexor carpi ulnaris, deltoideus anterior, biceps brachii caput breve and trapezius descendent. The results of the study showed a strong correlation between the theoretical indicator (Integrated Cycle Load) and the physiological indicator (root mean square of a normalized EMG amplitude from the 5 muscles). This proves that the developed theoretical indicator can be accepted as an indicator of upper limb musculoskeletal load during a work task.     

适应新威胁装甲车辆悬吊式乘员座椅设计

本文通过对适应新威胁装甲车辆悬吊式乘员座椅设计的安全性、舒适性、有效性的分析,以及对其悬吊系统、减震系统、材料结构等方面的研究,简要论述了国内外悬吊式座椅设计的发展情况,说明了研究新型座椅的紧迫性和必然性。     

Optimizing the performance of phase-change materials in personal protective clothing systems.

Phase-change materials (PCM) can be used to reduce thermal stress and improve thermal comfort for workers wearing protective clothing. The aim of this study was to investigate the effect of PCM in protective clothing used in simulated work situations. We hypothesized that it would be possible to optimize cooling performance with a design that focuses on careful positioning of PCM, minimizing total insulation and facilitating moisture transport. Thermal stress and thermal comfort were estimated through measurement of body heat production, body temperatures, sweat production, relative humidity in clothing and subjective ratings of thermal comfort, thermal sensitivity and perception of wetness. Experiments were carried out using 2 types of PCM, the crystalline dehydrate of sodium sulphate and microcapsules in fabrics. The results of 1 field and 2 laboratory experimental series were conclusive in that reduced thermal stress and improved thermal comfort were related to the amount and distribution of PCM, reduced sweat production and adequate transport of moisture.     

Investigation of seat belt use among the drivers of different education levels

Seat belt use habit has been investigated according to the education level of drivers. Copies of a questionnaire were distributed to 1000 participants of four different education levels. Factors such as seat belt usage habit, restricting factors and crash data have been investigated. Data have been analyzed with SPSS 15.0 software. Increased level of education leads to increased seat belt usage, lower numbers of crashes and crash severities. The factors restricting seat belt use are lack of habit, discomfort and short distance driving. The use of precaution signal and increases in comfort can increase seat belt usage. The primary and high school education on traffic safety and seat belt usage has been serving the purpose.     

Influence of Seat Properties on Occupant Dynamics in Severe Rear Crashes

Seat performance in retaining an occupant, transferring energy, and controlling neck responses is often questioned after severe rear crashes when fatal or disabling injury occur. It is argued that a stiffer seat would have improved occupant kinematics. However, there are many factors in occupant interactions with the seat. This study evaluates four different seat types in 26 and 32 mph (42 and 51 km/h), rear crash delta Vs. Two seats were yielding with k = 20 kN/m occupant load per displacement. One represented a 1970s yielding seat with j = 3.4°/kN frame rotation per occupant load, and 3 kN maximum load (660 Nm moment), and the other a high retention seat phased into production since 1997 with j = 1.4°/kN, and 10 kN maximum load (2200 Nm). Two seats were stiff with k = 40 kN/m. One represented a 1990s foreign benchmark with j = 1.8°/kN and a 7.7 kN maximum load (1700 Nm), and the other an all belts to seat (ABTS) with j = 1.0°/kN and 20 kN maximum load (4400 Nm). The crash was a constant acceleration of 11.8 g, or 14.5 g for 100 ms. Occupant interactions with the seat were modeled using a torso mass, flexible neck and head mass. By analysis of the equations of motion, the initial change in seatback angle (Δθ) is proportional to jk(y ? x), the product jk and the differential motion between the vehicle (seat cushion) and occupant. The transition from 1970s–80s yielding seats to stronger seats of the 1990s involved an increase in k stiffness; however, the jk property did not change as frame structures became stronger. The yielding seats of the 1970s had jk = 68°/m, while the stiff foreign benchmark seat had jk = 72°/m. The foreign benchmark rotated about the same as the 1970s seat up to 50 ms in the severe rear crashes. While it was substantially stronger, it produced higher loads on the occupant, and the higher loads increased seatback rotations and neck responses. The ABTS seat had the lowest rotations but also caused high neck responses because of the greater loads on the torso. Neck displacement (d) is initially proportional to (k/m_T) ∫∫ y, seat stiffness times the second integral of vehicle displacement divided by torso mass. As seat stiffness increases, head-torso acceleration, velocity, and neck displacement increase. This study shows that the jk seat property determines the initial seatback rotation in rear crashes. If a stronger seat has a higher stiffness, it rotates at higher loads on the occupant, reducing the overall benefit of the stronger frame, while increasing neck responses related to whiplash or neck extension prior to subsequent impacts. The aim of seat designs should be to reduce jk, provide pocketing of the pelvis, and give head-neck support for the best protection in severe rear crashes. For low-speed crashes, a low k is important to reduce early neck responses related to whiplash.     

Passenger use of and attitudes toward rear seat belts

Objectives: This study sought to identify attitudes toward belt use in the rear seat and to gain insight into the experiences of rear-seat passengers. Method: A telephone survey conducted between June and August 2016 targeted adult passengers who had recently ridden in the rear and who did not always wear their seat belt when doing so. Respondents were questioned regarding their reasons for not buckling up and possible conditions under which they would be more likely to buckle up during rear-seat travel. Results: Of 1163 recent rear-seat passengers, 72% reported always using their seat belt in the rear. Full-time belt use was lower among passengers who primarily travel in the rear of hired vehicles compared with personal vehicles. The most common explanation for not buckling up was that the back seat is safer than the front. Four out of five agreed they do not buckle up because of type of trip; two-thirds forget or do not see the need; and two-thirds agreed with reasons related to design, comfort, or usability issues. Nearly 40% agreed that they sometimes do not buckle up in the rear because there is no law requiring it. Conclusion: Many reasons for not using belts in the rear are similar to reasons in the front, such as forgetfulness, inconvenience, or discomfort. One difference is that many rear-seat passengers perceive using the belt is unnecessary because the back seat is safer than the front. More than half of part-time belt users and nonusers reported interventions such as rear seat belt reminders, stronger belt-use laws, and more comfortable belts would make them more likely to use their seat belt in the rear seat. Practical applications: This study identifies barriers to rear seat belt use that point to the need for a multi-faceted approach to increase belt use.     

Seat properties affecting neck responses in rear crashes: a reason why whiplash has increased

Whiplash has increased over the past two decades. This study compares occupant dynamics with three different seat types (two yielding and one stiff) in rear crashes. Responses up to head restraint contact are used to describe possible reasons for the increase in whiplash as seat stiffness increased in the 1980s and 1990s. Three exemplar seats were defined by seat stiffness (k) and frame rotation stiffness (j) under occupant load. The stiff seat had k=40 kN/m and j=1.8 degrees /kN representing a foreign benchmark. One yielding seat had k=20 kN/m and j=1.4 degrees /kN simulating a high-retention seat. The other had k=20 kN/m and j=3.4 degrees /kN simulating a typical yielding seat of the 1980s and 1990s. Constant vehicle acceleration for 100 ms gave delta-V of 6, 10, 16, 24, and 35 km/h. The one-dimensional model included a torso mass loading the seatback, head motion through a flexible neck, and head restraint drop and rearward displacement with seatback rotation. Neck displacement was greatest with the stiff seat due to higher loads on the torso. It peaked at 10 km/h rear delta-V and was lower in higher-severity crashes. It averaged 32% more than neck displacements with the 1980s yielding seat. The high-retention seat had 67% lower neck displacements than the stiff seat because of yielding into the seatback, earlier head restraint contact and less seatback rotation, which involved 16 mm drop in head restraint height due to seatback rotation in the 16 km/h rear delta-V. This was significantly lower than 47 mm with the foreign benchmark and 73 mm with the 1980s yielding seat. Early in the crash, neck responses are proportional to ky/mT, seat stiffness times vehicle displacement divided by torso mass, so neck responses increase with seat stiffness. The trend toward stiffer seats increased neck responses over the yielding seats of the 1980s and 1990s, which offers one explanation for the increase in whiplash over the past two decades. This is a result of not enough seat suspension compliance as stronger seat frames were introduced. As seat stiffness has increased, so have neck displacements and the Neck Injury Criterion (NIC). High-retention seats reduce neck biomechanical responses by allowing the occupant to displace into the seatback at relatively low torso loads until head restraint contact and then transferring crash energy. High-retention seats resolve the historic debate between stiff (rigid) and yielding seats by providing both a strong frame (low j) for occupant retention and yielding suspension (low k) to reduce whiplash.     

Seat influences on female neck responses in rear crashes: a reason why women have higher whiplash rates

Since the earliest crash investigations, whiplash has been found to occur more often in women than men. This study addresses seat properties that may explain a reason for the higher rates in women, and changes in whiplash in general over the past two decades. Three exemplar seats were defined on the basis of seat stiffness (k) and frame rotation stiffness (j) for rearward occupant load. Stiff seats have k=40 kN/m and j=1.8 degrees /kN representing a foreign benchmark loaded by a male. One yielding seat had k=20 kN/m and j=1.4 degrees /kN simulating a high-retention seat (1997 Grand Prix) and another k=20 kN/m and j=3.4 degrees /kN simulating a 1980s to 1990s yielding seat (1990 Buick Park Avenue). Constant vehicle acceleration for 100 msec gave delta-V of 6, 10, 16, and 24 km/h. The one-dimensional model included a torso mass loading the seatback with flexible neck and head mass. Based on biomechanical data and scaling, neck stiffness was 5 kN/m and 3 kN/m for the male and female, respectively. Based on validation tests, seat stiffness was 25% less with the female. Occupant dynamics were simulated in a step-forward solution based on the differential displacement between the head, torso, and seat up to head restraint contact. Neck responses were 30% higher in the female than male through most of the rear impact and are proportional to (kF/mTF)/(kM/mTM), which is the ratio of seat stiffness divided by torso mass for the female and male. Neck displacements were higher with the stiff seat than the 1990 C car seat for both the female and male. They peaked at 10 km/h and dropped off for higher severity crashes due to the shorter time to head contact. Neck displacements were greater in the female than male for the lowest severity crashes with the stiff and 1990 C car seats, when displacement was scaled for equal tolerance. The female in 1997 W car seat had the lowest neck displacements. Stiff seats increased neck displacements over the yielding seats of the 1980s in rear crashes. The trend is similar in men and women, but early neck displacements are greater in women because of a higher ratio of seat stiffness to torso mass. This implies that seat stiffness is not sufficiently low in proportion to the female mass in comparison to males. The j and k seat properties influence neck biomechanics and occupant dynamics, but k is important in determining early response differences between males and females.     

作业姿势舒适性评价研究

将人体划分为四个节段,并对每个节段的不同姿势进行编码,实现了维修作业姿势的参数化定义,由12位健康的男性被试者参加,根据主观感觉利用自由模量幅度估计法对这些姿势的舒适性进行了评价和分级,得出了各种作业姿势的舒适级别,实现了对作业姿势舒适性的定量评价。     

Passenger muscle responses in lane change and lane change with braking maneuvers using two belt configurations: Standard and reversible pre-pretensioner

Abstract

Objective: The introduction of integrated safety technologies in new car models calls for an improved understanding of the human occupant response in precrash situations. The aim of this article is to extensively study occupant muscle activation in vehicle maneuvers potentially occurring in precrash situations with different seat belt configurations.

Methods: Front seat male passengers wearing a 3-point seat belt with either standard or pre-pretensioning functionality were exposed to multiple autonomously carried out lane change and lane change with braking maneuvers while traveling at 73?km/h. This article focuses on muscle activation data (surface electromyography [EMG] normalized using maximum voluntary contraction [MVC] data) obtained from 38 muscles in the neck, upper extremities, the torso, and lower extremities. The raw EMG data were filtered, rectified, and smoothed. All muscle activations were presented in corridors of mean?±?one standard deviation. Separate Wilcoxon signed ranks tests were performed on volunteers’ muscle activation onset and amplitude considering 2 paired samples with the belt configuration as an independent factor.

Results: In normal driving conditions prior to any of the evasive maneuvers, activity levels were low (<2% MVC) in all muscles except for the lumbar extensors (3–5.5% MVC). During the lane change maneuver, selective muscles were activated and these activations restricted the sideway motions due to inertial loading. Averaged muscle activity, predominantly in the neck, lumbar extensor, and abdominal muscles, increased up to 24% MVC soon after the vehicle accelerated in lateral direction for all volunteers. Differences in activation time and amplitude between muscles in the right and left sides of the body were observed relative to the vehicle’s lateral motion. For specific muscles, lane changes with the pre-pretensioner belt were associated with earlier muscle activation onsets and significantly smaller activation amplitudes than for the standard belt (P?<?.05).

Conclusions: Applying a pre-pretensioner belt affected muscle activations; that is, amplitude and onset time. The present muscle activation data complement the results in a preceding publication, the volunteers’ kinematics and the boundary conditions from the same data set. An effect of belt configuration was also seen on previously published volunteers’ kinematics with lower lateral and forward displacements for head and upper torso using the pre-pretensioner belt versus the standard belt. The data provided in this article can be used for validation and further improvement of active human body models with active musculature in both sagittal and lateral loading scenarios intended for simulation of some evasive maneuvers that potentially occur prior to a crash.     

Influence of seat foam and geometrical properties on BioRID P3 kinematic response to rear impacts

As the primary interface with the human body during rear impact, the automotive seat holds great promise for mitigation of Whiplash Associated Disorders (WAD). Recent research has chronicled the potential influence of both seat geometrical and constitutive properties on occupant dynamics and injury potential. Geometrical elements such as reduced head to head restraint, rearward offset, and increased head restraint height have shown strong correlation with reductions in occupant kinematics. The stiffness and energy absorption of both the seating foam and the seat infrastructure are also influential on occupant motion; however, the trends in injury mitigation are not as clear as for the geometrical properties. It is of interest to determine whether, for a given seat frame and infrastructure, the properties of the seating foam alone can be tailored to mitigate WAD potential. Rear impact testing was conducted using three model year 2000 automotive seats (Chevrolet Camaro, Chevrolet S-10 pickup, and Pontiac Grand Prix), using the BioRID P3 anthropometric rear impact dummy. Each seat was distinct in construction and geometry. Each seat back was tested with various foams (i.e., standard, viscoelastic, low or high density). Seat geometries and infrastructures were constant so that the influence of the seating foams on occupant dynamics could be isolated. Three tests were conducted on each foam combination for a given seat (total of 102 tests), with a nominal impact severity of Delta V = 11 km/h (nominal duration of 100 msec). The seats were compared across a host of occupant kinematic variables most likely to be associated with WAD causation. No significant differences (p < 0.05) were found between seat back foams for tests within any given seat. However, seat comparisons yielded several significant differences (p < 0.05). The Camaro seat was found to result in several significantly different occupant kinematic variables when compared to the other seats. No significant differences were found between the Grand Prix and S-10 seats. Seat geometrical characteristics obtained from the Head Restraint Measuring Device (HRMD) showed good correlation with several occupant variables. It appears that for these seats and foams the head-to-head restraint horizontal and vertical distances are overwhelmingly more influential on occupant kinematics and WAD potential than the local foam properties within a given seat.     

Influence of Seat Foam and Geometrical Properties on BioRID P3 Kinematic Response to Rear Impacts

As the primary interface with the human body during rear impact, the automotive seat holds great promise for mitigation of Whiplash Associated Disorders (WAD). Recent research has chronicled the potential influence of both seat geometrical and constitutive properties on occupant dynamics and injury potential. Geometrical elements such as reduced head to head restraint, rearward offset, and increased head restraint height have shown strong correlation with reductions in occupant kinematics. The stiffness and energy absorption of both the seating foam and the seat infrastructure are also influential on occupant motion; however, the trends in injury mitigation are not as clear as for the geometrical properties. It is of interest to determine whether, for a given seat frame and infrastructure, the properties of the seating foam alone can be tailored to mitigate WAD potential. Rear impact testing was conducted using three model year 2000 automotive seats (Chevrolet Camaro, Chevrolet S-10 pickup, and Pontiac Grand Prix), using the BioRID P3 anthropometric rear impact dummy. Each seat was distinct in construction and geometry. Each seat back was tested with various foams (i.e., standard, viscoelastic, low or high density). Seat geometries and infrastructures were constant so that the influence of the seating foams on occupant dynamics could be isolated. Three tests were conducted on each foam combination for a given seat (total of 102 tests), with a nominal impact severity of Delta V = 11 km/h (nominal duration of 100 msec). The seats were compared across a host of occupant kinematic variables most likely to be associated with WAD causation. No significant differences (p < 0.05) were found between seat back foams for tests within any given seat. However, seat comparisons yielded several significant differences (p < 0.05). The Camaro seat was found to result in several significantly different occupant kinematic variables when compared to the other seats. No significant differences were found between the Grand Prix and S-10 seats. Seat geometrical characteristics obtained from the Head Restraint Measuring Device (HRMD) showed good correlation with several occupant variables. It appears that for these seats and foams the head-to-head restraint horizontal and vertical distances are overwhelmingly more influential on occupant kinematics and WAD potential than the local foam properties within a given seat.     

驾驶机舱LED灯光色温与人员警觉度关系仿真实验研究

为了探讨驾驶机舱内LED灯光色温与人员警觉度的联系,在A320模拟驾驶舱内设置2 500～2 700 K,3 000～3 200 K,6 000～6 500 K 3种不同色温的LED灯光环境,采用卡斯罗林嗜睡量表（KSS）、闪光融合临界频率仪（CFF）、视觉舒适度评分量表（VCS）,对5名被试人员在不同灯光环境的疲劳程度和视觉舒适度进行实时测量。针对测量结果,采用方差分析及描述性统计的数据分析方法,评价被试人员于不同灯光环境下的疲劳程度、视觉舒适度的差异性及变化情况。研究结果表明:高色温LED灯光环境下,人员的主观嗜睡感受及客观疲劳感受较低,且有着较低的疲劳感受增长率;高色温LED光源下人员的视觉舒适度也较高;增高LED灯光色温可一定程度上提升人员的警觉性。