Toward harmonizing prospective effectiveness assessment for road safety: Comparing tools in standard test case simulations

Abstract

Objective: With the overall goal to harmonize prospective effectiveness assessment of active safety systems, the specific objective of this study is to identify and evaluate sources of variation in virtual precrash simulations and to suggest topics for harmonization resulting in increased comparability and thus trustworthiness of virtual simulation-based prospective effectiveness assessment.

Methods: A round-robin assessment of the effectiveness of advanced driver assistance systems was performed using an array of state-of-the-art virtual simulation tools on a set of standard test cases. The results were analyzed to examine reasons for deviations in order to identify and assess aspects that need to be harmonized and standardized. Deviations between results calculated by independent engineering teams using their own tools should be minimized if the research question is precisely formulated regarding input data, models, and postprocessing steps.

Results: Two groups of sources of variations were identified; one group (mostly related to the implementation of the system under test) can be eliminated by using a more accurately formulated research question, whereas the other group highlights further harmonization needs because it addresses specific differences in simulation tool setups. Time-to-collision calculations, vehicle dynamics, especially braking behavior, and hit-point position specification were found to be the main sources of variation.

Conclusions: The study identified variations that can arise from the use of different simulation setups in assessment of the effectiveness of active safety systems. The research presented is a first of its kind and provides significant input to the overall goal of harmonization by identifying specific items for standardization. Future activities aim at further specification of methods for prospective assessments of the effectiveness of active safety, which will enhance comparability and trustworthiness in this kind of studies and thus contribute to increased traffic safety.     

让我们积极应对气候变化

气候确实在发生变化。以往人们随意地认为这与温室效应气体排放量的增加有关，现在这种观点已得到充分证实。自1991年以来．已出现了自有记录以来全球气温最高的十个年份．而在上个世纪，温度上升7约0.6摄氏度。在同一期间内，全球的海平面上升了约20厘米．部分原因是陆地上冰层融化．海洋自身发生热膨胀。许多山峰上的冰盖正在消失．最近几十年来，夏秋季节北冰洋的冰层厚     

Mitigation of the Impact of Tropical Cyclones in Northern Australia through Community Capacity Enhancement

Community mitigation of hazard impact requires hazard knowledge and preparedness on the part of the members of diverse and complex communities. Longitudinal research in the tropical cyclone prone north of Australia has gathered extensive datasets on community awareness, preparedness and knowledge, in order to contribute to education campaigns and mitigation strategies. Data have been used to identify issues of vulnerability to cyclones and capacity to deal with the hazard. This has been developed as a community vulnerability and capacity model that may be applied to diverse communities in order to assess levels of capability to mitigate and deal with the cyclone hazard. The model is presented here in a simplified form as its development is evolving and ongoing.     

Wind Dispersion: A Program for the Texas Instruments 59 Calculator

Simultaneous measurements of individual hydrocarbons and individual carbonyls were carried out at a downtown Los Angeles location. Concentrations are presented for 50 compounds in morning air samples. While paraffins (C ≥ 4) were a major hydrocarbon subclass on a ppmC basis, higher aromatics (C ≥ 8) were the major component when taking reactivity considerations into account. Comparison of the results with emission inventory data showed good agreement for many hydrocarbons and for paraffins as a subclass. Measured olefins and aromatics concentrations were substantially lower and higher, respectively, than those expected from inventory data.     

OPTIMAL IDENTIFICATION OF MUSKINGUM ROUTING COEFFICIENTS1

Traditionally, identification of the Muskingum routing coefficients has been based on observations of the linearity of a loop formed by graphically plotting a forward and a reverse path. This graphical procedure is time-consuming and may not minimize the error of estimation. A procedure was developed to improve the drawbacks of the graphical method. This procedure calls for (a) the use of least square regression on the forward and reverse paths to determine their respective slopes, and (b) the use of statistical t-test to evaluate the hypothesis that these two slopes are equal. The computational procedure is repeated, using incremental values of the flow weighting coefficient, x. A graph of the computed t-value versus x can be constructed. The optimal value of x, as read from the graph, occurs at the minimum computed t-value. The procedure has been demonstrated superior to the graphical method for three illustrative examples, resulting in a reduction of the error squares by factors ranging from 5 to 6.     

REVIEW ON GLOBAL NATURAL DISASTERS IN 2000

20 0 0ｗａｓａｒｅｌａｔｉｖｅｌｙｎｏｒｍａｌｙｅａｒｉｎｔｅｒｍｓｏｆｇｌｏｂａｌｄｉｓａｓｔｅｒｅｖｅｎｔｓ.Ｔｈｅｇｌｏｂａｌｌｏｓｓｆｒｏｍｎａｔｕｒａｌｄｉｓａｓｔｅｒｓｗａｓａｐｐｒｏｘｉｍａｔｅｌｙ 30ｂｉｌｌｉｏｎＵＳＤ ,ｗｈｅｒｅａｓｔｈａｔｉｎａｎｙｏｆｔｈｅｐｒｅｖｉｏｕｓｙｅａｒｓｈａｄｅｘｃｅｅｄｅｄ 1 0 0ｂｉｌｌｉｏｎＵＳＤ .Ｔｈｅｉｎｓｕｒａｎｃｅｌｏｓｓｉｎ 2 0 0 0ｗａｓｏｎｌｙ 8.3ｂｉｌｌｉｏｎＵＳＤ ,ｗｉｔｈ 92 0 0 ｐｅｒｓｏｎｓｋｉｌｌｅｄ .Ｔｈｅｒｅｗａｓｎ…     

A MATHEMATICAL MODEL OF SALMONID SPAWNING HABITAT1

ABSTRACT: A simulation model [Salmonid Spawning Analysis Model (SSAM)] was developed as a management tool to evaluate the relative impacts of stream sediment load and water temperature on salmonid egg survival. The model is useful for estimating acceptable sediment loads to spawning habitat that may result from upland development, such as logging and agriculture. Software in common use in the USA were adapted for use in gravel bedded rivers and linked to simulate water temperature (the USFWS Instream Water Temperature, SNTEMP model) and water and sediment routing (the USAE Scour and Deposition in Rivers and Reservoirs, HEC-6 model, version 3.2). These models drive the redd (spawning nest) model (the USDA-ABS Sediment Intrusion Dissolved Oxygen SIDO model) which simulates sediment intrusion and dissolved oxygen concentration in the redd environment. The SSAM model predictions of dissolved oxygen and water temperature compared favorably with field data from artificial redds containing hatchery chinook salmon eggs.     

FACTORS THAT AFFECT ACTIVATED SLUDGE PHOSPHATE RELEASE1

The activated sludge process can remove significant amounts of phosphorus from sewage, but the removal efficiency is usually significantly reduced by the release of phosphate back to solution during subsequent treatment steps. This research presents a study of soluble phosphate release from activated sludge with emphasis on defining the factors that affect such release and the actual release mechanisms. Laboratory units were used for experimental purposes. The experiments were designed to study the relationship between soluble phosphate release and various environmental factors such as redox potential (ORP), dissolved oxygen (DO), pH, solids concentration, solids destruction, and sulfate salt addition. The effect of substrate utilization on phosphate uptake and the relationship between uptake characteristics and subsequent phosphate release were also studied. The results show that some phosphate storage occurs during aerobic substrate utilization. Following substrate utilization, activated sludge phosphate release is directly related to the amount of biological stress the organisms are subjected to, and the mechanism of release is primarily cell lysis. The phosphate released per unit sludge under anoxic conditions is relatively constant. Under normal environmental conditions, neither ORP or pH change have a significant affect on phosphate release.