Key Engineering Materials Vols. 467-469

Abstract: Multiplicative problems are a kind of difficult global optimization problems known to be NP-hard. At the same time, these problems have some important applications in engineering, system, finance, economics, and other fields. In this paper, an optimization method is proposed to globally solve a class of multiplicative problems with coefficients. Firstly, by utilizing equivalent transformation and linearization method, a linear relaxation programming problem is established. Secondly, by using branch and bound technique, a determined algorithm is proposed for solving equivalent problem. Finally, the proposed algorithm is convergent to the global optimal solution of original problem by means of the subsequent solutions of a series of linear programming problems.

Abstract: The sum of linear fractional functions problem has attracted the interest of researchers and practitioners for a number of years. Since these types of optimization problems are non-convex, various specialized algorithms have been proposed for globally solving these problems. However, these algorithms are only for the case that sum of linear ratios problem without coefficients, and may be difficult to be solved. In this paper, a deterministic algorithm is proposed for globally solving the sum of linear fractional functions problem with coefficients. By utilizing an equivalent problem and linear relaxation technique, the initial non-convex programming problem is reduced to a sequence of linear relaxation programming problems. The proposed algorithm is convergent to the global optimal solution by means of the subsequent solutions of a series of linear programming problems.

Abstract: Volatile organic compounds (VOCs) are main type of indoor pollutants which are found in many workstation materials. In multi-layer work surface panels, different VOCs have different chemical and physical properties which will affect their transport properties and storage properties. Therefore, the VOC emission process and emission rate are generally different and depend on the type of VOCs. The effect of the initial condition, such as temperature, relative humidity, air change rate, initial VOC concentration and pollutant type are evaluated separately. This paper uses a build environment simulation (BES) program to investigate the effect of these factors on the VOC concentration in the air. Based on the theoretic analysis, several means can be adopted to reduce the pollutant emission and improve the indoor air quality (IAQ).

Abstract: The operating performance of listed companies is the comprehensive response on their quality of assets, operating state, development potential and so on. In this paper, evaluating indexes system which was used to evaluate the operating performance was provided combining with the feature of supplying water and gas listed companies in China. The performance evaluation model based on the factor analysis is established. As a case, the performance of 18 listed companies supplying water and gas in China is selected and evaluated. The case shows that the model is effective and can provide a basis for decision-making for enterprises improving management.

Abstract: This paper analysis on the design and the test of an air-conditioner hot water combined unit using environmental friendly refrigerant R407C. Firstly the research status of the system is elaborated for air-source heat pump water heater simply. Then the principle and structure are described on an air-conditioner heat pump followed by a water heater at different running modes and different operation conditions. The hot water experiments of the unit in three seasons have been tested and researched in a multi-functional environmental chamber. Some analysis of the unit’s thermodynamic performance is carried out from the test data for improving such kind of machine afterward.

Abstract: Physical Unclonable Function (PUF) is an excellent choice for key management in security domain. A Silicon PUF based RFID privacy protocol is proposed. Unlike general PUF applications which apply PUF in the tag-end, we employ PUF within a reader. Challenge -Responding Pairs (CRPs) on PUF in the proposal are reusable. Tag’s data structure is designed to a three level stack. Each level of the stack stands for a privacy state of the tag. State changing needs a password which only be transferred with plaintext. Password produce, storage, input/output operations are program control. We take a supermarket as application scene.

Abstract: User authentication is a key research domain in security. A user authentication scheme based on Physical Unclonable Function (PUF) is proposed. Unlike general PUF applications which apply PUF in the tag-end, we employ PUF within an Authentication Centre (AC), which is only used to verify a RFID tag is legal or not. When a tag is legal, the AC will send a password which is used only once to the request reader. The reader can use this password to decrypt the tag’s sensitive information which is encrypted with the same identical password. The later password which is used in encryption is produced and used only once within the tag.

Abstract: Tooth is a kind of biomaterial in nature. It behaves favorable strength, stiffness and fracture toughness, which are closely related to its fine microstructure. The observation of scanning electron microscope (SEM) on a mature tooth shows that the tooth is a kind of natural bioceramic composite consisting of hydroxyapatite layers and collagen protein matrix. The observation also shows that the hydroxyapatite layers consist of long and thin hydroxyapatite sheets and that all the hydroxyapatite sheets are arranged in a kind of parallel distribution. The maximum pullout energy of the hydroxyapatite sheets, which is closely related to the fracture toughness of the tooth, is investigated based on the representative model of the parallel distribution. It shows that the long and thin shape as well as the parallel distribution of the hydroxyapatite sheets increase the maximum pullout energy and enhance the fracture toughness of the tooth.

Abstract: Scanning electron microscope (SEM) observation shows that the shell of a Unio douglasiae is a kind of bioceramic composite consisting of laminated aragonite and organic materials. The aragonite layers further consist of thin and long aragonite fibers. The aragonite fibers possess high density in the shell and their diameter is within nanometer scale. The mechanism of the high modulus and high strength of the shell were investigated based on the observed nanometer structure of the aragonite fibers and the rule of mixtures Young’s modulus as well as the Griffith criterion. It reveals that the high density and the nanometer scale of the aragonite fibers endow the shell with high modulus and fracture strength.

Abstract: Composite materials not only have good mechanical performances but also have excellent durability and ability to be formed into complex shape. So advanced composite materials are used extensively in ship industry. In the composite ship structure the T-joint is one of the common joint in practice. As the main load-bearing structure of ship, the mechanical and reliability designs of T-joint are the important aspects of the ship structure design. The traditional composite T-joint is bonded joint, and adhesive strength has obvious influence on the properties of T-joint. To improve the properties of composite T-joint, in this paper the bolted composite T-joint is chosen for studying. Finite element method is used to investigate the properties of bolted T-joint. The influences of bolt-clamping load and friction coefficient on the stress distribution of bolt-hole edge are investigated. Some conclusions can be used as references for the design of bolted composite T-joint.