手机短信模块在.NET平台下实现与应用

首先介绍了用于手机短信的串口通信、AT指令以及发送模式等相关知识,然后重点解析了手机短信的编码方法,包括7-bit编码和UCS2编码等,并给出了在.NET平台下用C#实现的主要代码。文章最后还描述了手机短信模块在某一个实际的监视系统中的集成与应用场景。     

Interfacial reaction mode and its influence on tensile strength in laser joining Al alloy to Ti alloy

Abstract

In order to obtain a robust dissimilar joint of Al/Ti alloys, a filler wire of Al–12 wt-%Si and 45° V shape groove on the base metal were used during CO₂ laser welding. Heat input had evident influence on the interfacial reaction mode. It was found that a dissolution mode for low heat input and a melting mode for high heat input exist at the joint interface, which was analysed from thermodynamic point of view. Tensile strength of the joints in the dissolution mode reached as high as 296 MPa, which was significantly higher than that in the melting mode.     

Solidification cracking in low alloy steel welds

Abstract

The high solidification cracking susceptibility of low C steel weld metals was investigated using pure Fe model alloys containing 0–0·23%C, 0–5%Ni and 0–0·0144%B. In addition, a few Fe–C–Ni ternary alloys were also tested. Solidification cracking susceptibility was tested using longitudinal varestraint and transvarestraint tests. Cracking was evaluated using crack length and brittleness temperature range criteria. The Fe–C alloys showed high cracking tendency in two regimes, the first in the ultralow carbon range of 0·03–0·05%C and the second in a narrow band close to 0·1%C. The cracking was much more than that attributable to solute segregation. In Fe–Ni and Fe–B alloys, cracking was a function of alloy content. Solidification cracking due to C and Ni was higher in the ferritic mode of solidification compared to the austenitic, unlike in stainless steels, where the ferritic mode provides high resistance to cracking. In Fe-C-Ni ternary alloys, cracking could be better related to composition in terms of a variable coefficient for C in the Ni equivalent. In the vicinity of 0·1%C, cracking was attributable to shrinkage due to solid state transformation from δ to γ in the brittle temperature range, and is similar to that occurring during continuous casting of steel. However, this factor did not appear to play a role in cracking in the ultralow C range of 0·03–0·05%C.     

Low temperature chemical synthesis of nanosized ceramic powders

Abstract

A variety of nanosized (particle dia. <100 nm) ceramic powders have been prepared from metal ion complex based precursor solutions. The precursor solution was prepared at room temperature from metal hydroxides, nitrates, or acetates mixed with suitable complexing agents such as amines, carboxylic acids, hydroxy carboxylic acids, or poly-hydroxy compounds. Calcination of the precursor mass at low external temperatures produces the nanosized ceramic powders. The examples discussed include perovskites, i.e. lead zirconate titanate PbZr_0·6 Ti_0·4O₃(PZT) and lead magnesium niobate PbMg_1/3 Nb_2/3 O₃ (PMN).     

Driving Mode Decision in the Obstacle Negotiation of a Variable Single-Tracked Robot

We propose a new algorithm for obstacle negotiation of a mobile robot known as a variable single-tracked robot (VSTR). The robot was originally designed for the purpose of rescue operations; hence, its ability to traverse various environments should be guaranteed. Previous experiments have already shown that the special structural characteristics of a VSTR enable it to easily climb indoor stairs. However, the VSTR has a critical drawback in that all of its functions are realized by an operator and the robot cannot detect obstacles or transform its driving mode by itself. For this reason, we have enhanced the system with the basis for autonomous navigation, i.e., the ability to negotiate obstacles, and we have introduced a methodology for practical use. Our experiments confirm that the driving mode decision, which is controlled by position-sensitive detector infrared sensors, gives decisive improvement. Moreover, the experimental results show that the robot can overcome several obstacles, thereby reflecting the benefits of the proposed algorithm.     

Fracture mechanics approach to forecast delamination lifetime

Interlaminar fracture (delamination) is one of the major concerns in the design of laminated composite structures, adhesive joints, coatings, sealants and other multilayered material systems. Service lifetime of a laminated structure is limited by the time an interlaminar flaw propagates to a size perceived critical to the stiffness and/or the strength of the structure. The time required to cause certain magnitude of delamination, under stresses below the initiation stress, could be forecasted if the constitutive equation for the rate of delamination is known. This paper describes an approach to develop the constitutive equation for delamination under mode I conditions. The approach rests on principles of linear elastic fracture mechanics (LEFM) and uses elevated temperature to accelerate interlaminar fracture at constant loads. The experiments used double cantilever beam test specimens fabricated as a model system from poly(methyl methacrylate) (PMMA) beams and epoxy adhesive whose stiffness was equivalent to that of a typical carbon/epoxy laminated composite. Mechanistic observations indicated that the fracture front displayed similar mechanism at all test conditions. A modified form of Paris power law is suggested to forecast service lifetime in terms of temperature, service load and the initial flaw size.     

Development of a novel crawler mechanism with polymorphic locomotion

The design of a novel crawler mechanism with polymorphic locomotion is presented in this paper. The proposed mechanism, which is equipped with a planetary gear reducer, provides two kinds of outputs in different form only using one actuator. By determining the reduction ratio of two outputs in a suitable proportion, the crawler mechanism is capable of switching between two locomotion modes autonomously according to terrain. Using this property, robots equipped with the crawler mechanism can perform more efficient and adaptable locomotion or posture in irregular environments. Experimental tests showed that the developed crawler-driven module equipped with the proposed crawler mechanism cannot only move on moderately rugged terrain, but also perform a particular locomotion mode to negotiate high obstacles or adapt to different terrains without any sensors for distinguishing obstacles or any extra actuators or mechanisms for assistance.     

Risk assessment in pressure equipment inspection: review of recent applications in Jiangsu

Abstract

The application of risk based inspection (RBI) technology in five typical cases in Jiangsu Province, China was summarised and reviewed. Based on 10 year experiences of risk assessment, some key problems, which require special attention in the process of publicising and applying RBI technology in China, were put forward, and the integrity management of pressurised equipment and the qualification requirement for organisation undertaking the RBI projects were emphasised as well. Responses to RBI demands from Chinese petrochemical enterprises were analysed and recommended to be categorised into three groups. To conduct RBI successfully in China, the importance of combining a first rank RBI software and a well organised RBI team is proposed. A sinicised database of materials and chemicals owing to Chinese intellectual property is suggested to be built gradually as well.     

Dynamic characteristics of adhesive bonded high strength steel joints

Abstract

With an increase in the use of advanced high strength steels in vehicle architectures, materials joining issues have become increasingly important. Among the various joining methods, adhesive bonding is increasingly used in automobile manufacturing. Successful implementation of adhesive bonding to improve structural crashworthiness and reduce vehicle weight requires the knowledge of issues related not only to processing but also to joint performance. In this study, the impact strength of adhesive bonded high strength steel joints is evaluated with the split Hopkinson tension bar (SHTB) technique. The influences of loading speed and thickness of the steels on the shear strength of the joints were examined. Comparative quasi-static lap shear tests were also conducted on a tensile testing machine. Test results showed that strength and energy absorption of bonded steel joints increase with loading speed, and is greatly affected by the thickness of the steels. As the loading rates are increased to 1100 s^–1 (i.e. 20 m s^–1), bonded 0·75 mm thick DP600 steel shows a 152% increase in strength and an 83% increase in energy absorption when compared to its quasi-static values. Examination of the impact tested specimens showed the failure mode changes from coarse cohesive mode to fine cohesive mode with increasing loading speed. The results from this study will provide the information for a better understanding of impact failure mechanisms of adhesive bonded high strength steels.     

Optimum design of co-cured steel–composite tubular single lap joints under axial load

In this paper, an optimum design method for co-cured steel-composite tubular single lap joints under axial load is proposed based on a failure model which incorporates the nonlinear mechanical behavior of the steel adherend and the failure mode of joints such as composite adherend failure and steel adherend failure. The design parameters considered were the test temperature, the stacking sequence of the composite adherends, the thickness ratio of the steel adherend to the composite adherend, and the existence of scarf in the steel adherend. Stress analysis of the cocured steel-composite tubular single lap joints was performed considering the nonlinear mechanical behavior of the steel adherend, and the fabrication residual thermal stress and thermal degradation of the composite adherend. The method developed may be employed in the joining of hybrid composite structures such as golf clubs and automotive composite propeller shafts in which a carbon/epoxy shaft has normally been bonded to a metal shaft with epoxy adhesives.