Applied Mechanics and Materials Vols. 110-116

Abstract: In this paper the wavelength conversion in a 1cm long silicon-on-insulator (SOI) waveguide has been investigated numerically. The wavelength conversion efficiency is optimized by analyzing free carriers absorption (FCA) loss generated by two-photon-absorption (TPA). The free carriers life time is focused while other factors influencing noise figure are also considered.

Abstract: The Time Projection Chamber of the ALICE ex- periment at the CERN Large Hadron Collider features highly integrated on-detector read-out electronics. It is following the general trend of high energy physics experiments by placing the front-end electronics as close to the detector as possible—only some 10 cm away from its active volume. Being located close to the beams and the interaction region, the electronics is subject to a moderate radiation load, which allowed us to use commercial off-the-shelf components. However, they needed to be selected and qualified carefully for radiation hardness and means had to be taken to protect their functionality against soft errors, i. e. single event upsets. Here we report on the first measurements of LHC induced radiation effects on ALICE front-end electronics and on how they attest to expectations.

Abstract: To obtain the maximum luminous efficiency from an organic material, it is necessary to harness both the spin-symmetric and anti-symmetric molecular excitations (bound electron–hole pairs, or excitons) that result from electrical pumping. Here, we demonstrate that this deficiency can be overcome by using a phosphorescent sensitizer to excite a fluorescent dye. The photoluminescence and sensitization effect between tris (2-phenylpyridine) iridium (Ir (ppy) 3) and 5,6,11,12-tetraphenylnaphthacene (rubrene) in the host of 4,4'-N,N-dicarbazole-biphenyl (CBP) were investigated. The energy transfer characteristics in the electroluminescent process of the system of CBP, Ir (ppy) 3 and Rubrene has been discuss in this article. The Ir (ppy) 3 sensitizer affords an effective way to improve the device performance. In the organic light-emitting diodes based on the Ir (ppy) 3, rubrene and CBP system, both the singlet and triplet excitons can be used.

Abstract: With the increase of the difficulty and intensity on competitive movement, the rate of sport injury will happen in training and competing frequently. The metatarsal is one of the most prone to injury part in the human body. The incidence of metatarsal injuries is rising in recently years. In this study, Pedar-X plantar pressure measure system and Novel emed pressure distribution measure plate were used in order to get the dynamics data in normal landing and inverted landing. The research concluded that: metatarsal peak stress had been transferred from the first metatarsal to the fifth metatarsal with increasing of varus angle. When the foot was in inverted state, stress distribution of metatarsal changed significantly. Lateral metatarsal played a major role in supporting function. Also, forefoot pressure distribution changed a lot in different functional sports shoes. The purpose is to provide the reliable correlative theoretical basis for improving sport equipments and security protection recommendations for people to engage in sports.

Abstract: In airplanes, engine mounting structures have two primary performances: 1-They sustain all loads which engines produces or those which are exerted on engines in different maneuvering conditions. 2-They make the thrust load and the centric line of its containing cabin concentric [1]. In this paper, analysis of a mounting engine structure with the purpose of the accurate adjustment of the engine in its cabin is presented. Some sample diagrams, which introduced ideal adjustment angles for a specific aircraft, is proposed. These diagrams are obtained with the help of a MATLAB program that can be used for any dimension of the engine and cabin. Therefore, with the aid of these diagrams or this code, the time of adjustment the engine in its cabin will be decreased so much.

Abstract: The size of fuel propulsive droplets is one of the effective parameter in improvement of the mixture of air and fuel as well as combustion. The effects of Pressure on the average diameter of fuel propulsive droplets sizing and effective mass fraction in a duct are numerically investigated in the present paper. We named the mass of fuel vapor inside the flammability limit as the efficient mass fraction. The inlet pressure of entrance airflow is varied as 1, 2, 3, 4 and 5 (atm) to examine its effects on the fuel droplets and fuel/air mixing phenomena. As well, by growing the entrance air flow velocity from 36 to 50 (m/s) we have repeated this test again, which provides worthwhile information for the combustor design work. To fulfill the calculations a modified version of KIVA-3V code which is a transient, three-dimensional, multiphase, multicomponent code for the analysis of chemically reacting flows with sprays, is used.

Abstract: In this paper, free vibration differential equations of cracked beam are solved by using differential transform method (DTM) that is one of the numerical methods for ordinary and partial differential equations. The Euler–Bernoulli beam model is proposed to study the frequency factors for bending vibration of cracked beam with ant symmetric boundary conditions (as one end is clamped and the other is simply supported). The beam is modeled as two segments connected by a rotational spring located at the cracked section. This model promotes discontinuities in both vertical displacement and rotational due to bending. The differential equations for the free bending vibrations are established and then solved individually for each segment with the corresponding boundary conditions and the appropriated compatibility conditions at the cracked section by using DTM and analytical solution. The results show that DTM provides simple method for solving equations and the results obtained by DTM converge to the analytical solution with much more accurate for both shallow and deep cracks. This study demonstrates that the differential transform is a feasible tool for obtaining the analytical form solution of free vibration differential equation of cracked beam with simple expression.

Abstract: This paper investigates the dynamics and control of a charged two-craft tether formation in elliptical orbit. Due to the fact that the inter-spacecraft Coulomb forces are not sufficient to stabilize the tether, a method of hybrid control is proposed which uses conventional thrusts and Coulomb forces. A feedback control law is developed which could asymptotically stabilize the tether size and attitude while mitigating plume impingement issues. The equations governing this system are periodic in time, thus a feedback control using constant gains can not work. A periodic control law is suggested basing on Floquet theory. The control law consists of two main parts. First Floquet transformation is utilized to transform the system into a new linear system with a constant state matrix but a periodic control matrix. Then a feedback control is used to stabilize the new system. Numerical examples are provided to demonstrate the performance of the control law.

Abstract: Although the quality of a completed engine ready for shipping is traditionally assured by adopting the firing run at the final process of the engine assembly line, we have still not readily accepted the testing of engines in cold state i.e. without actual combustion & continue to neglect all its long term benefits in view of the immediate shortcomings which not only enhances the inspection speed, fault detection but also poses zilch threat to the environment around us. It increases the effectiveness of the “In-Process Quality Control” of an Engine production line.

Abstract: With the rapid development of information technology, some experience intensive work like fault detecting has been greatly improved by information technology. Traditional fault detecting method depends on the knowledge of expert to some extent which can not satisfy the requirement of large engine, which is with poor testability. Regarding this problem, this paper apply the technology of Independent Components Analysis (ICA) and BP neutral network to the process of fault detecting, the accuracy and efficiency are greatly improved with these methods, and the experiment result has proven the validity of the method described.