预压托换桩在深基坑临近建筑物加固及边坡支护的应用研究

煤矿输煤暗道基坑开挖时造成临近主井驱动机房倾斜和基坑边坡垮塌。采用钢筋混凝土预压托换桩对原主井驱动机房基础加固,通过托换桩将机房荷载传递到承载力较好的持力层,既保证了既有建筑物的安全,又保证了边坡的稳定,加固效果可靠,取得了良好的经济与社会效益,为既有建筑近旁开挖深基坑的边坡支护方法的研究与工程应用方面取得了成功的尝试。     

海峡西岸沿海地区经济发展与环境保护协调性研究

随着国家"一带一路"战略的深入,海峡西岸沿海地区进入新一轮快速发展阶段."工业补课"为主要模式的工业发展带动下,海西地区二产长期占主导地位,且呈现出明显的工业重型化特征.石化、火电等产业为主的沿海产业带初具规模,资源推动型、投资拉动型经济发展特征明显,导致生态用地占用、资源环境超载等环境问题凸显.建议海西地区快速发展中,首先确定、维护好区域及城市的生态环境功能定位,以此作为促进经济社会与环境保护协调发展的基础.     

Near crash characteristics among risky drivers using the SHRP2 naturalistic driving study

Problem: Previous research have focused extensively on crashes, however near crashes provide additional data on driver errors leading to critical events as well as evasive maneuvers employed to avoid crashes. The Strategic Highway Research Program 2 (SHRP2) Naturalistic Driving Study contains extensive data on real world driving and offers a reliable methodology to study near crashes. The current study utilized the SHRP2 database to compare the rate and characteristics associated with near crashes among risky drivers. Methods: A subset from the SHRP2 database consisting of 4,818 near crashes for teen (16–19 yrs), young adult (20–24 yrs), adult (35–54 yrs), and older (70+ yrs) drivers was used. Near crashes were classified into seven incident types: rear-end, road departure, intersection, head-on, side-swipe, pedestrian/cyclist, and animal. Near crash rates, incident type, secondary tasks, and evasive maneuvers were compared across age groups. For rear-end near crashes, near crash severity, max deceleration, and time-to-collision at braking were compared across age. Results: Near crash rates significantly decreased with increasing age (p < 0.05). Young drivers exhibited greater rear-end (p < 0.05) and road departure (p < 0.05) near crashes compared to adult and older drivers. Intersection near crashes were the most common incident type among older drivers. Evasive maneuver type did not significantly vary across age groups. Near crashes exhibited a longer time-to-collision at braking (p < 0.01) compared to crashes. Summary: These data demonstrate increased total near crash rates among young drivers relative to adult and older drivers. Prevalence of specific near crash types also differed across age groups. Timely execution of evasive maneuvers was a distinguishing factor between crashes or near crashes. Practical Applications: These data can be used to develop more targeted driver training programs and help OEMs optimize ADAS to address the most common errors exhibited by risky drivers.     

Pedestrians under influence (PUI) crashes: Patterns from correspondence regression analysis

Introduction: Alcohol-related impairment is a key contributing factor in traffic crashes. However, only a few studies have focused on pedestrian impairment as a crash characteristic. In Louisiana, pedestrian fatalities have been increasing. From 2010 to 2016, the number of pedestrian fatalities increased by 62%. A total of 128 pedestrians were killed in traffic crashes in 2016, and 34.4% of those fatalities involved pedestrians under the influence (PUI) of drugs or alcohol. Furthermore, alcohol-PUI fatalities have increased by 120% from 2010 to 2016. There is a vital need to examine the key contributing attributes that are associated with a high number of PUI crashes. Method: In this study, the research team analyzed Louisiana’s traffic crash data from 2010 to 2016 by applying correspondence regression analysis to identify the key contributing attributes and association patterns based on PUI involved injury levels. Results: The findings identified five risk clusters: intersection crashes at business/industrial locations, mid-block crashes on undivided roadways at residential and business/residential locations, segment related crashes associated with a pedestrian standing in the road, open country crashes with no lighting at night, and pedestrian violation related crashes on divided roadways. The association maps identified several critical attributes that are more associated with fatal and severe PUI crashes. These attributes are dark to no lighting, open country roadways, and non-intersection locations. Practical Applications: The findings of this study may be used to help design effective mitigation strategies to reduce PUI crashes.     

Consequential cognition: Exploring how attribution theory sheds new light on the firm‐level consequences of product recalls

It is unclear why some firms suffer greater negative consequences than others following a product recall. To shed light on this question, we extend attribution theory to the firm level to explore how consumers engage in an attributional process following product recalls that shapes their responses to firms. Integrating attribution theory and the demand side theoretical perspective, we assert that consumer judgments of responsibility toward manufacturers are shaped by causal data regarding the locus of causality (i.e., manufacturer or supplier) and controllability (i.e., prior knowledge or awareness) of a recalled product's potential for harm. We then examine the impact of product recall characteristics on judgments of responsibility and firm‐level outcomes using an experimental test involving responses from 320 subjects. Our findings suggest that judgments of responsibility are attributed to the manufacturing firm more when consumers are given causal information indicating that the firm is the source of, or is aware of, a product's defects. The results also indicate that judgments of responsibility can have costly firm‐level consequences in the form of reputational damage, diminished consumer purchase intentions, and increased legal damage recommendations. We discuss theoretical contributions, practical implications, and opportunities for further research.     

The Illinois .08 law. An evaluation

Lowering state blood alcohol concentration (BAC) limits to 0.08, though controversial, has been supported by most evaluation studies to date. The Illinois .08 BAC law implemented in 1997 provided a unique opportunity to evaluate the effect of the law without the simultaneous passage of an administrative license revocation (ALR) law, which has clouded some previous evaluations of the .08 laws. The proportion of all drinking drivers in fatal crashes was compared before versus after implementing the .08 law using time-series analysis to evaluate 12 years of fatal crash data for Illinois and five bordering states. The results showed that the proportion of drinking drivers in fatal crashes decreased by 14% in Illinois and increased by 3% in bordering states. The proportion of drinking drivers in fatal crashes in Illinois, though increasing since 1995, was sharply reduced after passage of the .08 law in 1997, saving more than 100 lives in 1998 and 1999 than it would have without the .08 law.     

利用侧光光纤优化生物反应器固定CO_2的研究

为了研究Chlorella sp.固定CO2的效果,降低能耗,采用自制生物光照反应器并选用侧光光纤作为光源。实验结果表明,在适宜条件下,通入浓度为10%CO2后,Chlorella sp.的生长明显加快。当选择红光和蓝光作为侧光光纤的光源交替运行,2 mm与3 mm光纤各28根耦合于16 W的光源发生器,较120 W LED外置光源而言,每瓦可提升6倍的生长速率。     

Using conditional inference forests to identify the factors affecting crash severity on arterial corridors

Introduction

The study aims at identifying traffic/highway design/driver-vehicle information significantly related with fatal/severe crashes on urban arterials for different crash types. Since the data used in this study are observational (i.e., collected outside the purview of a designed experiment), an information discovery approach is adopted for this study.

Method

Random Forests, which are ensembles of individual trees grown by CART (Classification and Regression Tree) algorithm, are applied in numerous applications for this purpose. Specifically, conditional inference forests have been implemented. In each tree of the conditional inference forest, splits are based on how good the association is. Chi-square test statistics are used to measure the association. Apart from identifying the variables that improve classification accuracy, the methodology also clearly identifies the variables that are neutral to accuracy, and also those that decrease it.

Results

The methodology is quite insightful in identifying the variables of interest in the database (e.g., alcohol/ drug use and higher posted speed limits contribute to severe crashes). Failure to use safety equipment by all passengers and presence of driver/passenger in the vulnerable age group (more than 55 years or less than 3 years) increased the severity of injuries given a crash had occurred. A new variable, ‘element’ has been used in this study, which assigns crashes to segments, intersections, or access points based on the information from site location, traffic control, and presence of signals.

Impact

The authors were able to identify roadway locations where severe crashes tend to occur. For example, segments and access points were found to be riskier for single vehicle crashes. Higher skid resistance and k-factor also contributed toward increased severity of injuries in crashes.     

Motorcyclist perception response time in stopping sight distance situations

One of the most effective engineering measures is the provision of an exclusive motorcycle lane that separates motorcycles from other mixed traffic to reduce traffic congestion and motorcycle crashes. Even though the existing exclusive motorcycle lanes in Malaysia reduced the incidents of motorcycle crashes with other vehicles, the design of this special motorcycle lane was based on a cross reference between a bicycle track and a highway. Thus, a suitable design guide is yet to be developed for the geometrical design of a proper and safer exclusive motorcycle lane. Safe stopping sight distance (SSD) has been recognized as a criterion for road design and should be taken into account. Motorcyclist perception response time (PRT) is the time from detection object until the rider reduces motorcycle speed in braking action is an essential component of motorcycle SSD. Two road experiments were conducted to obtain empirical values of motorcycle PRT to expected and unexpected objects. In the expected condition, 89 motorcyclists applied brake as quickly as possible following activation of a light beside the road. In the unexpected condition, 16 riders responded by braking in response to an obstacle that appeared suddenly in their lane. The mean PRT to expected and unexpected object is 0.71 s and 1.25 s respectively. The 85th percentile PRT to unexpected object is 2.12 s. This study found that most riders are capable of responding to an unexpected object along the roadway in 2.5 s or less. Therefore, PRT of 2.5 s is an appropriate value for motorcycle lane geometric design.     

Roadside design assessment in an urban,low-density environment in the Gulf Cooperation Council region

Objectives: Proper roadside design is crucial in order to mitigate the consequences associated with single-vehicle run-off-road (SVROR) crashes. However, the Gulf Cooperation Council (GCC) region lacks in-depth, detailed information on its roadside design status. Hence, there is a need for an in-service evaluation of roadside design in the GCC region. The objective of this study is to assess the existing roadside design in a medium-sized, low-density city in the United Arab Emirates (UAE).

Methods: A multiyear crash database was used to identify 116 locations where SVROR injury crashes occurred between 2013 and 2016 in the city of Al Ain in the UAE. Visits to these locations were made in order to assess their roadside design. Subsequently, the collected data were analyzed. Roadside design was classified based on whether or not it deviated from roadside design guidelines. The guidelines adopted as a benchmark were those contained in the 2012 Abu Dhabi Department of Transport Roadside Design Guide (RDG) and/or those in the 2011 American Association of State Highway and Transportation Officials (AASHTO) RDG. It is worth stressing that local guidelines are heavily based on the 2011 AASHTO RDG.

Results: The study found that almost one quarter of all SVROR crashes resulted in injuries. The study also found that a staggering 80.17% of the SVROR injury crashes investigated occurred at locations where roadside design deviated from the benchmark. Lack of an adequate clear zone was the main cause of noncompliant locations. Most SVROR injury crash locations containing roadside design with deviations from the benchmark were located on roads with posted speed limits of 100 kph or higher. Light poles, trees, curbs, and barriers were the most harmful objects most often struck, and tree collisions accounted for the highest number of severe crashes. Ninety-four and 86% of all studied locations containing light poles and trees, respectively, were found to be noncompliant with the benchmark. Twenty-eight percent of all SVROR injury crashes involved a rollover. All rollovers were preceded by a collision with a tree, pole, guardrail, or curb. Forty-four percent of all rollover crashes resulted in severe injuries.

Conclusions: Significant revision of the existing roadside design not only in the area studied but throughout the UAE is recommended. The authors propose measures that may be useful in making roadside design in the area studied better align with the benchmark requirements.