基于平均飞行航迹的CCO减噪效用研究

近年来，通过优化飞行程序降低机场飞机噪声影响成为机场环境保护的重要研究方向。文章首先建立了基于飞机“噪声-功率-距离”数据的噪声计算模型，介绍了平均飞行航迹以及连续爬升运行(Continuous Climb Opera-tion, CCO)离场程序的相关理论，最后以大型国际机场为实例，使用飞机平均飞行航迹进行噪声预测，运用综合噪声模型计算出噪声影响面积并绘制噪声影响等值线图，比较了CCO离场相对常规的标准仪表离场(Standard Instru-ment Departure, SID)的降噪效果。结果表明，CCO离场程序可有效降低机场噪声影响，在高噪声级影响区域的降噪效果更佳。     

Trends in mortality due to motor vehicle traffic accident injuries between 1987 and 2011 in a Spanish region (Comunitat Valenciana)

Objective

To analyse the time evolution of the rates of mortality due to motor vehicle traffic accidents (MVTA) injuries that occurred among the general population of Comunitat Valenciana between 1987 and 2011, as well as to identify trend changes by sex and age group.

Methods

An observational study of annual mortality trends between 1987 and 2011. We studied all deaths due to MVTA injuries that occurred during this period of time among the non-institutionalised population residing in Comunitat Valenciana (a Spanish Mediterranean region that had a population of 5,117,190 inhabitants in 2011). The rates of mortality due to MVTA injuries were calculated for each sex and year studied. These rates were standardised by age for the total population and for specific age groups using the direct method (age-standardised rate – ASR). Joinpoint regression models were used in order to detect significant trend changes. Additionally, the annual percentage change (APC) of the ASRs was calculated for each trend segment, which is reflected in statistically significant joinpoints.

Results

For all ages, ASRs decrease greatly in both men and women (70% decrease between 1990 and 2011). In 1990 and 2011, men have rates of 36.5 and 5.2 per 100,000 men/year, respectively. In the same years, women have rates of 8.0 and 0.9 per 100,000 women/year, respectively. This decrease reaches up to 90% in the age group 15–34 years in both men and women. ASR ratios for men and women increased over time for all ages: this ratio was 3.9 in 1987; 4.6 in 1990; and 5.8 in 2011. For both men and women, there is a first significant segment (p < 0.05) with an increasing trend between 1987 and 1989–1990. After 1990, there are 3 segments with a significant decreasing APC (1990–1993, 1993–2005 and 2005–2011, in the case of men; and 1989–1996, 1999–2007 and 2007–2011, in the case of women).

Conclusion

The risk of death due to motor vehicle traffic accidents injuries has decreased significantly, especially in the case of women, for the last 25 years in Comunitat Valenciana, mainly as of 2006. This may be a consequence of the road-safety measures that have been implemented in Spain and in Comunitat Valenciana since 2004. The economic crisis that this country has undergone since 2008 may have also been a contributing factor to this decrease.Despite the decrease, ASR ratios for men and women increased over time and it is still a high-risk cause of death among young men. It is thus important that the measures that helped decrease the risk of death are maintained and improved over time.     

Application of accelerated carbonation with a combination of Na2CO3 and CO2 in cement-based solidification/stabilization of heavy metal-bearing sediment

The efficient remediation of heavy metal-bearing sediment has been one of top priorities of ecosystem protection. Cement-based solidification/stabilization (s/s) is an option for reducing the mobility of heavy metals in the sediment and the subsequent hazard for human beings and animals. This work uses sodium carbonate as an internal carbon source of accelerated carbonation and gaseous CO₂ as an external carbon source to overcome deleterious effects of heavy metals on strength development and improve the effectiveness of s/s of heavy metal-bearing sediment. In addition to the compressive strength and porosity measurements, leaching tests followed the Chinese solid waste extraction procedure for leaching toxicity – sulfuric acid and nitric acid method (HJ/T299-2007), German leaching procedure (DIN38414-S4) and US toxicity characteristic leaching procedures (TCLP) have been conducted. The experimental results indicated that the solidified sediment by accelerated carbonation was capable of reaching all performance criteria for the disposal at a Portland cement dosage of 10 wt.% and a solid/water ratio of 1:1. The concentrations of mercury and other heavy metals in the leachates were below 0.10 mg/L and 5 mg/L, respectively, complying with Chinese regulatory level (GB5085-2007). Compared to the hydration, accelerated carbonation improved the compressive strength of the solidified sediment by more than 100% and reduced leaching concentrations of heavy metals significantly. It is considered that accelerated carbonation technology with a combination of Na₂CO₃ and CO₂ may practically apply to cement-based s/s of heavy metal-bearing sediment.     

Identification of stiffness tensor components of wood cell walls by means of nanoindentation

A new procedure to characterize the full set of elastic constants of wood cell walls was developed. For the first time, not only the longitudinal modulus, but also the transverse- and the shear modulus were determined in one experimental setup at micron scale. For this purpose, nanoindentation experiments were performed at variable angles between the indentation direction and the direction of cellulose microfibrils in wood cell walls. Using an approach based on anisotropic indentation theory a relationship between the indentation moduli obtained experimentally and the elastic material constants of the cell wall was derived. Using an error minimization procedure, the values of the elastic material constants were finally calculated. As typically observed for natural materials, our experimental results are characterized by high variability. Particularly the elastic modulus in longitudinal cell direction is highly sensitive to small changes in the local orientation of cellulose microfibrils. Nonetheless, reasonable estimates of 26.3 GPa for the longitudinal elastic modulus of the secondary wood cell wall S2, 4.5 GPa for the transverse modulus, and – for the first time – a value of 4.8 GPa for the shear modulus of wood cell wall material were obtained.     

A decision making methodology for material selection using an improved compromise ranking method

An ever increasing variety of materials is available today, with each having its own characteristics, applications, advantages, and limitations. In choosing the right material, there is not always a single definite attribute of selection and the designers and engineers have to take into account a large number of material selection attributes. This paper presents a logical procedure for material selection for a given engineering application. The procedure is based on an improved compromise ranking method considering the material selection attributes and their relative importance for the application considered. Two examples are included to illustrate the approach.     

Identification of the elastic and damping properties in sandwich structures with a low core-to-skin stiffness ratio

A mixed numerical–experimental identification procedure for estimating the storage and loss properties in sandwich structures with a soft core is developed. The proposed method uses at the experimental level a precise measurement setup with an electro-dynamic shaker and a scanning laser interferometer, and at the computational level an original structurally damped shell finite element model derived from the higher-order shear deformation theory with piecewise linear functions for the through-the-thickness displacement. The parameter estimation is derived from adequate objective functions measuring the discrepancy between the experimental and numerical modal data. Through a sensitivity analysis it is shown that for sandwich structures with a soft core only one specimen is required for characterizing the dominant properties of both the core and the skins. The procedure is then applied to two test cases for which all the influent elastic properties and the major damping parameters could be estimated with a fairly good precision.     

On using exponential basis functions for laminates modeled by CLPT,FSDT and TSDT: Further tests and results

In this paper we present some results from the application of a mesh-free method introduced previously (Compos Struct 2011;93:3112–9 and 94:84–91) for bending analysis of laminated composite plates. This method is applicable to a wide range of bending problems without limitation in the stacking sequence of the laminated plates and the boundary conditions. Herein, two specific types of problems, having traction free boundaries, are examined and the issues related to the solution of them are addressed. Also as new benchmark problems, some more results for cross-ply and angle-ply composites are presented.     

Results of the Queensland 2007–2012 roadside drug testing program: The prevalence of three illicit drugs

The purpose of this investigation is to present an overview of roadside drug driving enforcement and detections in Queensland, Australia since the introduction of oral fluid screening. Drug driving is a problematic issue for road safety and investigations of the prevalence and impact of drug driving suggest that, in particular, the use of illicit drugs may increase a driver's involvement in a road crash when compared to a driver who is drug free. In response to the potential increased crash involvement of drug impaired drivers, Australian police agencies have adopted the use of oral fluid analysis to detect the presence of illicit drugs in drivers. This paper describes the results of roadside drug testing for over 80,000 drivers in Queensland, Australia, from December 2007 to June 2012. It provides unique data on the prevalence of methamphetamine, cannabis and ecstasy in the screened population for the period. When prevalence rates are examined over time, drug driving detection rates have almost doubled from around 2.0% at the introduction of roadside testing operations to just under 4.0% in the latter years. The most common drug type detected was methamphetamine (40.8%) followed by cannabis (29.8%) and methamphetamine/cannabis combination (22.5%). By comparison, the rate of ecstasy detection was very low (1.7%). The data revealed a number of regional, age and gender patterns and variations of drug driving across the state. Younger drivers were more likely to test positive for cannabis whilst older drivers were more likely to test positive for methamphetamine. The overall characteristics of drivers who tested positive to the presence of at least one of the target illicit drugs are they are likely to be male, aged 30–39 years, be driving a car on Friday, Saturday or Sunday between 6:00 pm and 6:00 am and to test positive for methamphetamine.     

Comparative study of European tunnel emergency-stop-area-wall protection measures

Due to the increasing number of traffic accidents involving the collisions of vehicles with the emergency-stop-area head walls in tunnels, a comparative numerical analysis in accordance with the EN 1317 standard has been performed in order to assess the quality of the available protective safety barriers. Based on the simulation results, the values of the relevant injury criteria – the acceleration severity index (ASI), the theoretical head impact velocity (THIV) and the post-impact head deceleration (PHD) – were computed for several collision scenarios involving two different passenger vehicles colliding with two different safety barriers in various ways. The results show that due to the geometrical restrictions in the tunnel's emergency stop area none of the barriers can provide total protection for the occupants of the vehicle in the event of a collision. The installation of a steel-sheet-tube crash cushion was, however, found to provide the best possible protection within the given limitations. The results of the analysis were the basis for selecting a safety-barrier design for existing tunnel installations and for the proposed changes in regulations governing the geometry of the tunnel's emergency stop area.     

Computation of limit and shakedown loads using a node‐based smoothed finite element method

This paper presents a novel numerical procedure for computing limit and shakedown loads of structures using a node‐based smoothed FEM in combination with a primal–dual algorithm. An associated primal–dual form based on the von Mises yield criterion is adopted. The primal‐dual algorithm together with a Newton‐like iteration are then used to solve this associated primal–dual form to determine simultaneously both approximate upper and quasi‐lower bounds of the plastic collapse limit and the shakedown limit. The present formulation uses only linear approximations and its implementation into finite element programs is quite simple. Several numerical examples are given to show the reliability, accuracy, and generality of the present formulation compared with other available methods. Copyright © 2011 John Wiley & Sons, Ltd.     

On Testing for the Degree of a Polynomial

Two methods are presented for deciding upon the proper degree of a polynomial regression function. One is based on a sequential F test and the other uses a two sample procedure. Both methods assume that the classical regression model is applicable. These methods enable one to realize desired guarantees against choosing either too small or too large a degree, which is not true for current fixed size sample methods.     

Injury typology of fatal motorcycle collisions with roadside barriers in Australia and New Zealand

Motorcyclists contribute significantly to road trauma around the world through the high incidence of serious injuries and fatalities. The role of roadside safety barriers in such trauma is an area of growing concern amongst motorcyclists, road authorities and road safety researchers and advocates. This paper presents a case series analysis of motorcyclists that were fatally injured following a collision with a roadside barrier during the period 2001–2006 in Australia and New Zealand. Injury profiles and severities are detailed, and associations with crash characteristics are investigated. It is shown that the thorax region had the highest incidence of injury and the highest incidence of maximum injury in fatal motorcycle-barrier crashes, followed by the head region. This is in contrast to fatal motorcycle crashes in all single- and multi-vehicle crash modes, where head injury predominates. The injury profiles of motorcyclists that slid into barriers and those that collided with barriers in the upright posture were similar. However, those that slid in were more likely to receive thorax and pelvis injuries.     

The integral catcher analysis of nuclear recoil experiments

The integral thick target thick catcher equations for extracting excitation and relaxation recoil velocities of nuclear reaction products have been reformulated. The new data analysis scheme corrects certain limitations and deficiencies inherent in the conventional procedure. Like the latter, our integral catcher analysis uses forward and backward recoil fractions F and B, but has no constraints on target thickness. The utility of the method may be extended with advantage to thinner targets. Additionally, there are no restrictions on the form of the range-velocity relationship that can be employed. Finally, the procedure inherently provides an excellent evaluation of the statistical uncertainties in the derived velocities based on the experimental uncertainties in F and B.     

Impact of mandating a driving lesson for older drivers at license renewal in Japan

In Japan, a driving lesson consisting of a lecture, a driver aptitude test, on-road driving assessment and a discussion session was added to the driving license renewal procedure for drivers aged 75 years or older in 1998 and for drivers aged 70 years or older in 2002. We investigated whether these additions contributed to a reduction in at-fault motor vehicle collisions (MVCs) by examining the trend of the at-fault MVC rates per licensed driver and the rate ratios of the older drivers relative to those aged 65–69 years for the years 1986–2011. All data were derived from nationwide traffic statistics. If the introduction of the lesson was effective in reducing at-fault MVCs of older drivers, the rate ratio should have declined, given that the lesson targeted only the older drivers. We found this was not the case, i.e., there was no declining trend in the at-fault MVC rate ratios of both drivers aged 75 years or older and drivers aged 70 years or older, relative to drivers aged 65–69 years, after the driving lesson at license renewal became mandatory for these older drivers. Therefore, the mandatory lesson for the older drivers at license renewal needs to be reconsidered.     

Nonuniform transformation field analysis of elastic–viscoplastic composites

To exactly describe the macroscopic behaviour of composites with non linear dissipative constituents, it is necessary to take an infinitely large number of internal variables into account. Simplifying assumptions are usually adopted to reduce this number. A new method has been proposed [Michel JC, Suquet P. Nonuniform transformation field analysis. Int J Solids Struct 2003;40:6937–55], based on the transformation fields approach [Dvorak G. Transformation field analysis of inelastic composite materials. Proc Roy Soc Lond A 1992;437:311–27], but not taking transformation fields to be necessarily uniform. The interest of this new method has been shown in the case of composites with elastic–plastic constituents. Here we deal with composites having elastic–viscoplastic and porous elastic–viscoplastic constituents. In the latter case, the viscoplastic strain has a dilatational part.     

Exploration and comparison of crash modification factors for multiple treatments on rural multilane roadways

As multiple treatments (or countermeasures) are simultaneously applied to roadways, there is a need to assess their combined safety effects. Due to a lack of empirical crash modification factors (CMFs) for multiple treatments, the Highway Safety Manual (HSM) and other related studies developed various methods of combining multiple CMFs for single treatments. However, the literature did not evaluate the accuracy of these methods using CMFs obtained from the same study area. Thus, the main objectives of this research are: (1) develop CMFs for two single treatments (shoulder rumble strips, widening shoulder width) and one combined treatment (shoulder rumble strips + widening shoulder width) using before–after and cross-sectional methods and (2) evaluate the accuracy of the combined CMFs for multiple treatments estimated by the existing methods based on actual evaluated combined CMFs. Data was collected for rural multi-lane highways in Florida and four safety performance functions (SPFs) were estimated using 360 reference sites for two crash types (All crashes and Single Vehicle Run-off Roadway (SVROR) crashes) and two severity levels (all severity (KABCO) and injury (KABC)).     

Facile and versatile method for preparing core–shell microspheres with controlled surface structures based on silica particles-monolayer

This paper introduces a facile method for preparing core–shell type particles composed of a polymer core and a controlled layer shell with inorganic particles such as SiO₂, TiO₂ and Fe₃O₄. This method can be characterized as a one-pot synthesis procedure based on self-assembling copolymerization. By choosing particle diameters and adjusting the chemical modification of inorganic shell components, the method enables precise control of a shell layer such as single, double and multi-layer structures.     

Reproducing kernel collocation method applied to the non-linear dynamics of pipe whip in a plane

A windowed collocation method, based on a moving least squares reproducing kernel particle approximation of functions, is explored for spatial discretization of the strongly non-linear system of partial differential equations governing large, planar whipping motion of a cantilever pipe subjected to a follower force pulse (the blow-down force) normal to the deflected centreline at its tip. This problem was discussed by Reid et al. [An elastic–plastic hardening–softening cantilever beam subjected to a force pulse at its tip: a model for pipe whip. Proc R Soc London A1998;454:997–1029] where a space–time finite difference discretization was employed to solve the governing partial differential equation of motion. It was shown that, despite the deflected shape predictions being accurate, numerical solutions of these equations might exhibit problematic (possibly spurious) steep localized gradients. The resolution of this problem in the context of structural mechanics is novel and is the subject of this paper. In particular, it is demonstrated that it is possible to reduce significantly such spurious and localized numerical instabilities through a windowed collocation approach with a suitable choice of the window size. The collocation procedure presently adopted is based on the moving least squares reproducing kernel particle method. Material and structural non-linearity in the beam (pipe) model is incorporated via an elastic–plastic-hardening–softening moment–curvature relationship. The projected ordinary differential equations are then integrated in time through a fifth order, explicit Runge–Kutta method with adaptive step sizes.     

Determining quantitative road safety targets by applying statistical prediction techniques and a multi-stage adjustment procedure

Due to substantial progress made in road safety in the last ten years, the European Union (EU) renewed the ambitious agreement of halving the number of persons killed on the roads within the next decade. In this paper we develop a method that aims at finding an optimal target for each nation, in terms of being as achievable as possible, and with the cumulative EU target being reached. Targets as an important component in road safety policy are given as reduction rate or as absolute number of road traffic deaths. Determination of these quantitative road safety targets (QRST) is done by a top-down approach, formalized in a multi-stage adjustment procedure. Different QRST are derived under consideration of recent research. The paper presents a method to break the national target further down to regional targets in case of the German Federal States. Generalized linear models are fitted to data in the period 1991–2010. Our model selection procedure chooses various models for the EU and solely log-linear models for the German Federal States. If the proposed targets for the EU Member States are attained, the sum of fatalities should not exceed the total value of 15,465 per year by 2020. Both, the mean level and the range of mortality rates within the EU could be lowered from 28–113 in 2010 to 17–41 per million inhabitants in 2020. This study provides an alternative to the determination of safety targets by political commitments only, taking the history of road fatalities trends and population into consideration.     

The design of protection circuitry for high-frequency ultrasound imaging systems

Transmission line lengths in the protection circuitry of a high-frequency (>20-MHz) ultrasound imaging system have an important effect on the frequency, amplitude, and bandwidth of the pulse-echo response of the system. A model that includes the transmission line lengths between the pulser, transducer, and receiver and the electromechanical properties of high-frequency transducers is used to illustrate the importance of correctly choosing these line lengths. An iterative optimization procedure for designing the protection circuitry for a broadband system is proposed. A theoretical and experimental analysis of the validity of this approach is reported for a 45-MHz PVDF transducer.