Effects of vehicle impact velocity, vehicle front-end shapes on pedestrian injury risk

Objective: This study aimed at investigating the effects of vehicle impact velocity, vehicle front-end shape, and pedestrian size on injury risk to pedestrians in collisions with passenger vehicles with various frontal shapes. Method: A series of parametric studies was carried out using 2 total human model for safety (THUMS) pedestrian models (177 and 165?cm) and 4 vehicle finite element (FE) models with different front-end shapes (medium-size sedan, minicar, one-box vehicle, and sport utility vehicle [SUV]). The effects of the impact velocity on pedestrian injury risk were analyzed at velocities of 20, 30, 40, and 50?km/h. The dynamic response of the pedestrian was investigated, and the injury risk to the head, chest, pelvis, and lower extremities was compared in terms of the injury parameters head injury criteria (HIC), chest deflection, and von Mises stress distribution of the rib cage, pelvis force, and bending moment diagram of the lower extremities. Result: Vehicle impact velocity has the most significant influence on injury severity for adult pedestrians. All injury parameters can be reduced in severity by decreasing vehicle impact velocities. The head and lower extremities are at greater risk of injury in medium-size sedan and SUV collisions. The chest injury risk was particularly high in one-box vehicle impacts. The fracture risk of the pelvis was also high in one-box vehicle and SUV collisions. In minicar collisions, the injury risk was the smallest if the head did not make contact with the A-pillar. Conclusion: The vehicle impact velocity and vehicle front-end shape are 2 dominant factors that influence the pedestrian kinematics and injury severity. A significant reduction of all injuries can be achieved for all vehicle types when the vehicle impact velocity is less than 30?km/h. Vehicle designs consisting of a short front-end and a wide windshield area can protect pedestrians from fatalities. The results also could be valuable in the design of a pedestrian-friendly vehicle front-end shape. [Supplementary materials are available for this article. Go to the publisher's online edition of Traffic Injury Prevention for the following free supplemental resource: Head impact conditions and injury parameters in four-type vehicle collisions and validation result of the finite element model of one-box vehicle and minicar. ].     

氢气爆炸特性研究

本文研究、总结了氢气与空气(氢气与氧气)的混合物的爆炸特性.即氢气在空气中,在比较低燃烧界限的情况下,只有向上的传播和非常少的超压可以观测得到.正因为氢气的这种特性,将氢应用于科技将极大地推进社会进步,氢燃料将成为一种主要的能源.然而,氢技术应用的成功与否主要取决于氢使用的安全性.所以,必须掌握实际使用时氢气燃烧的性能.本文在日本过去十年实验数据的基础上,通过实验研究了氢气与空气混合物的燃点.研究了氢气、氧气混合物经氮气稀释后,按化学当量比例将不同浓度的氢气与空气进行混合,并得出了低温下的爆炸压力特性.随后,分别讨论了在初始压力下一致的情况下,试管直径相同的状况下,氢气与空气混合浓度相同的情况下,这三种爆轰传播限制之间的关系.得出了在空气中直接点燃的发生爆轰的最小试管直径,最小的装药量之间的关系,进行了爆轰危险性分级.最后,文章概括比较了氢与其他燃料的燃烧特性,评估了氢气燃烧过程中的危险与安全因素.     

Development of a catalytic dehalogenation (Cl,Br) process for municipal waste plastic-derived oil

Dehalogenation is a key technology in the feedstock recycling of mixed halogenated waste plastics. In this study, two different methods were used to clarify the effectiveness of our proposed catalytic dehalogenation process using various carbon composites of iron oxides and calcium carbonate as the catalyst/sorbent. The first approach (a two-step process) was to develop a process for the thermal degradation of mixed halogenated waste plastics, and also develop dehalogenation catalysts for the catalytic dehydrochlorination of organic chlorine compounds from mixed plastic-derived oil containing polyvinyl chloride (PVC) using a fixed-bed flow-type reactor. The second approach (a single-step process) was the simultaneous degradation and dehalogenation of chlorinated (PVC) and brominated (plastic containing brominated flame retardant, HIPS–Br) mixed plastics into halogen-free liquid products. We report on a catalytic dehalogenation process for the chlorinated and brominated organic compounds formed by the pyrolysis of PVC and brominated flame retardant (HIPS–Br) mixed waste plastics [(polyethylene (PE), polypropylene (PP), and polystyrene (PS)], and also other plastics. During dehydrohalogenation, the iron- and calcium-based catalysts were transformed into their corresponding halides, which are also very active in the dehydrohalogenation of organic halogenated compounds. The halogen-free plastic-derived oil (PDO) can be used as a fuel oil or feedstock in refineries.     

Emission inventory of deca-brominated diphenyl ether (DBDE) in Japan

Atmospheric emissions of deca-brominated diphenyl ether (DBDE) in Japan were estimated based on the material flow of DBDE products and their emission factors. In 2002, the demand for DBDE in Japan was 2200 ton/year and the stock level was about 60 000 ton. The DBDE flow into the waste stream was estimated to be about 6000 ton/year and the flow out through second-hand product exports was more than 700 ton/year. Home appliance recycling facilities dismantle and crush domestic wastes containing about 600 ton of DBDE annually. Material recycling of crushed plastics is not commonly practiced as yet. Emission factors from plastics processing (2 × 10⁻⁹–1 × 10⁻⁷), textile processing (9 × 10⁻⁷), home appliance recycling (8 × 10⁻⁹–5 × 10⁻⁶), and waste incineration (1 × 10⁻⁷–2 × 10⁻⁶) were estimated using field measurement data. The DBDE emission rate through house dust during the service life of final products (2 × 10⁻⁷–9 × 10⁻⁷ per year) was estimated using the DBDE concentration in dust and the amount of dust in used televisions. Emission factors from previous studies were also used. The estimated total DBDE emission was 170–1800 kg/year. These results suggest the necessity of characterizing emissions during the service life of products, which is essential information for formulating an appropriate e-waste recycling strategy.     

Determination of persistent organic pollutants by gas chromatography/laser multiphoton ionization/time-of-flight mass spectrometry

An authentic mixture of polychlorinated biphenyls was measured using a short wide-bore capillary column for the group separation of major components present in an actual sample of Kanechlor. The limits of detection were improved by ca. 2 fold in comparison with those obtained using a conventional capillary column, since the retention time was reduced and the amount of analytes introduced into the mass spectrometer per unit time could be increased. On the other hand, surface-water and sediment samples containing polycyclic aromatic hydrocarbons (PAHs) were collected from the river located in the vicinity of a waste water treatment plant. Even acenaphthylene, a minor component of the mixture could be measured for the sediment sample, and the concentrations were determined for several heavy PAHs. As demonstrated, a technique involving laser multiphoton ionization/time-of-flight mass spectrometry was useful as a sensitive and selective analytical tool for the trace analysis of persistent organic pollutants in an environmental sample.     

Transport and transformation of sulfur compounds over East Asia during the TRACE-P and ACE-Asia campaigns

On the basis of the recently estimated emission inventory for East Asia with a resolution of 1×1°, the transport and chemical transformation of sulfur compounds over East Asia during the period of 22 February through 4 May 2001 was investigated by using the Models-3 Community Multi-scale Air Quality (CMAQ) modeling system with meteorological fields calculated by the regional atmospheric modeling system (RAMS). For evaluating the model performance simulated concentrations of sulfur dioxide (SO₂) and aerosol sulfate (SO₄²⁻) were compared with the observations on the ground level at four remote sites in Japan and on board aircraft and vessel during the transport and chemical evolution over the Pacific and Asian Pacific regional aerosol characterization experiment field campaigns, and it was found that the model reproduces many of the important features in the observations, including horizontal and vertical gradients. The SO₂ and SO₄²⁻ concentrations show pronounced variations in time and space, with SO₂ and SO₄²⁻ behaving differently due to the interplay of chemical conversion, removal and transport processes. Analysis of model results shows that emission was the dominant term in regulating the SO₂ spatial distribution, while conversion of SO₂ to SO₄²⁻ in the gas phase and the aqueous phase and wet removal were the primary factors that controlled SO₄²⁻ amounts. The gas phase and the aqueous phase have the same importance in oxidizing SO₂, and about 42% sulfur compounds (25% in SO₂) emitted in the model domain was transported out, while about 57% (35% by wet removal processes) was deposited in the domain during the study period.     

Effects of light quality on initiation and development of meroplanktonic diatom blooms in a eutrophic shallow sea

We investigated the effects of light quality on resting stage cell germination and vegetative cell growth of meroplanktonic diatoms in a small port in Hakata Bay, Japan and in the laboratory. During the investigation over the year of 2006, the meroplanktonic diatom bloom first occurred in the end of May and then repeated wane and wax until October in the small port. From late April to middle May, light penetrating the water column was often strong and attenuations of all spectral lights were low. During this period, Skeletonema costatum, Thalassiosira minima, and Chaetoceros sp. appeared frequently, followed by the blooms of S. costatum and Chaetoceros sp. in late May. Thereafter, S. costatum and Chaetoceros sp. bloomed in late June but not in middle June, when pigmented flagellates bloom appeared. The attenuation of short-wavelength light such as violet and blue lights was markedly high during these diatom and flagellate blooms; all blooms disappeared within several days. Vegetative cell strains of the three diatoms under light emitting diodes (LEDs) with six different spectra (violet, blue, green, orange, red, and near-infrared) grew at a higher rate under short-wavelength light, violet and blue. On the other hand, when suspensions of bottom sediments from Hakata Bay were cultured under the same LEDs and in the dark, vegetative cells of S. costatum appeared under all LEDs except for orange and near-infrared, vegetative cells of T. minima appeared under all LEDs but not in the dark, and vegetative cells of Chaetoceros sp. appeared under violet and blue LEDs. However, vegetative cell densities of the three diatoms increased much more under violet light than under other LEDs within a short period (6 days). Our study indicates that underwater penetration by short-wavelength light, such as violet and blue, may be an important factor in the initiation and development of meroplanktonic diatom blooms.     

Quantification of free and esterified long-chain fatty acids without extraction by high-performance liquid chromatography in anaerobic digestion sludge

Journal of Material Cycles and Waste Management - During anaerobic digestion, the concentrations of long-chain fatty acids (LCFAs) need to be monitored to achieve good performance due to their...     

Greenhouse gas reduction potential by household waste prevention

Journal of Material Cycles and Waste Management - We used a life-cycle assessment (LCA) approach to estimate the greenhouse gas (GHG) reduction effects of preventing 50% of all avoidable household...     

Situational characteristics of fatal pedestrian accidents involving vehicles traveling at low speeds in Japan

Abstract

Objective: This study aimed to investigate the situational characteristics of fatal pedestrian accidents involving vehicles traveling at low speeds in Japan. We focused on vehicles with 4 or more wheels. Such characteristics included daytime or nighttime conditions, road type, vehicle behaviors preceding the accident, and vehicle impact locations.

Methods: Pedestrian fatality data on vehicle–pedestrian accidents were obtained from the Institute for Traffic Accident Research and Data Analysis of Japan (ITARDA) from 2005 to 2014. Nine vehicle classifications were considered: Trucks with gross vehicle weight (GVW) ≥7.5 tons and <7.5 tons, buses, box vans, minivans, sport utility vehicles (SUVs), sedans, light passenger cars (LPCs), and light cargo vans (LCVs). We compared the situational daytime or nighttime conditions, road type, vehicle behaviors preceding the accident, and vehicle impact locations for accident-involved vehicles traveling at low and higher speeds across all vehicle types.

Results: The results indicate that pedestrian fatalities involving vehicles traveling at low speeds occurred more often under daytime conditions across all vehicle types. At signalized intersections, the relative proportions of pedestrian fatalities were significantly higher when vehicles were traveling at low speed, except when the accidents involved box vans or SUVs. Similarly, when vehicles turned right, the relative proportions of pedestrian fatalities were significantly higher when vehicles traveling at low speed were involved across all vehicle types. In terms of the frontal right vehicle impact location, the relative proportions of pedestrian fatalities were significantly higher when trucks with GVW ≥7.5 tons or <7.5 tons, sedans, or LCVs traveling at low speed were involved.

Conclusions: The situational characteristics of fatal pedestrian accidents involving vehicles traveling at low speeds identified in this study can guide targeted development of new traffic safety regulations or technologies specific to vehicle–pedestrian interactions at low vehicle travel speeds (i.e., driver alert devices or automated emergency braking systems). Ultimately, these developments can improve pedestrian safety by reducing the frequency or severity of vehicle–pedestrian accidents for vehicles turning right at intersections and/or reducing the number of resultant pedestrian fatalities.