Air Bending Process for Load Optimised Profiles

In this paper the air bending of Tailor Rolled Blanks (TRB) to load optimised profiles is investigated. A new flexible modular tool system has been developed in order to locally adapt the die height to the spring back which is more pronounced in thinner areas in comparison to thicker areas of the TRB. With the new tool system the dies can be modulated according to the thickness distribution of the Tailor Rolled Blank, whereas the amount of die lifting depends on the thickness difference and the corresponding variance of mechanical properties. In bending tests with several specimens having a constant thickness a linear relation between the increasing part angle and a stepwise increased die lifting was observed. With this linear dependency the amount of die lifting can be calculated and thus applied on bending of TRB. Special consideration is required for the die adjustment in the area of the linear thickness transition, therefore three different die arrangements have been investigated. The results of different bending tests are compared and evaluated in order to apply the new technique to form a new car body floor structure in profile intensive construction. By using load optimised profiles in combination with a steel 22MnB5 which has been heat‐treated at defined sections the survival space of a car passenger in a side pole impact has been enormously increased by more than 40 %.     

Automated optimal design of a two-stage helical gear reducer

The design space of multi-stage transmissions is usually very large and heavily constrained. This places significant demands on the algorithm employed to search it, but successful optimization has the potential to yield considerably better designs than conventional heuristics, at the same time enabling a better understanding of the trade-offs between various objectives (such as service life and overall weight). Here we tackle a two-stage helical gear transmission design problem (complete with the sizing and selection of shafts, bearings, housing, etc.) using a two-phase evolutionary algorithm in a formulation that can be extended to include additional stages or different layouts.     

年轻的战争

正在编辑这期杂志的时候,恰逢两个“节日”即将来临——南非世界杯和全国高考。其实他们都不是真正的节日,但是都被人高度关注：世界杯是全世界球迷的节日,而高考却属于中国的一代年轻人。每年到了6月初,广播电视、报纸网络都会铺天盖地、不惜笔墨地报道这一“盛事”,不是节日这是什么。     

A survey of biometric technology based on hand shape

Automated biometric systems have emerged as a more reliable alternative to the traditional personal identification solutions. One of the most popular biometrics is hand shape due to its ease of use, non-intrusiveness and public acceptance. This paper presents a survey of the technology used in hand shape-based biometric systems. We first review the component modules including the algorithms they employ. Next we discuss system taxonomies, performance evaluation methodologies, testing issues and US government evaluations. A summary of the accuracy results reported in the literature is also provided. We next describe some of the commercial hand shape biometric systems as well as some recent successful deployments. Finally, we mention a few limitations of the hand shape biometric and give some directions for future research.     

Cerebral effects in superior vena caval cannula obstruction: the role of brain monitoring

A pediatric cardiac case of transient obstruction of the superior vena cava by the venous cannula before cardiopulmonary bypass is presented. With venous obstruction and increase in central venous pressure, reduced cerebral blood flow velocities and absence of diastolic Doppler flow were detected. This was followed by regional cerebral venous oxygen desaturation and global electroencephalographic slowing. Reposition of the venous cannula led to the recovery of these physiologic indicators and a noncomplicated clinical outcome.     

Effect of precursor concentration on structural,morphological and opto-electric properties of ZnO thin films prepared by spray pyrolysis

Sprayed ZnO films were grown on glass substrate at 400 °C using zinc chloride as precursor with different molar concentrations varying from 0.05 to 0.2 M. X-ray diffraction patterns reveal that ZnO films are polycrystalline with hexagonal wurtzite structure with preferred orientation in (002) plane. Optical measurements show that transmittance reaches a maximum value of 95% in the visible region for ZnO films prepared from precursor with 0.05 M concentration. The films obtained from the precursor with 0.1 M concentration have the highest electrical conductivity and photocurrent values.     

The influence of the additives composition and concentration on the properties of SnOx thin films used in photocatalysis

The aim of this study is to investigate the influence of different organic additives on the surface properties of SnO_x thin films used for photocatalytic degradation of methylene blue. The films were obtained by anodic oxidation of tin substrate in electrolyte solutions containing green additives based on hydrophobic and hydrophilic maleic anhydride copolymers. The hydrophobic copolymer leads to the formation of thin films with increased specific area which generates a larger interfacial area between the layers and the dye solution. The consequence is an improvement in the photocatalytic efficiency: up to 16% compared to less than 5% for samples electrodeposited without polymer. The hydrophilic copolymer presence in the electrolyte solution leads to higher grain size and lower surface energy which significantly reduce the photocatalytic properties of the layers. The use of copolymers can be a tool for enhancing the surface roughness and film's wettability and thus the photodegradation efficiency.     

Opto-electronic properties of SnO2 layers obtained by SPD and ECD techniques

The paper presents a comparative approach concerning the properties of SnO₂ thin layers obtained via spray pyrolysis deposition (SPD) and electro-chemical deposition (ECD). The influences of crystalline structure (X-ray diffraction), morphology (atomic force microscopy, contact angle) on the electric (electrical conductivity) properties of the layers were studied. The SPD samples present a porous morphology with high surface energy compared with ECD samples characterized by a dense morphology. The photocatalytic efficiency of the samples was tested in the photodegradation of methylene blue and the higher values (57%) correspond to SPD samples.