Prediction of crushing stress in composite materials

A simple mathematical model for predicting the crushing stress of composite materials was derived and presented in this paper. The present knowledge of fracture mechanics and strength of materials are used as the basis for the model. The fracture mechanics part of the analysis was based on energy release rate approach; the energy release rate, G, of the proposed model was determined by this approach. This energy release rate was based on the Mode I (opening or tensile mode) failure. As for the strength of materials part analysis, buckling theory was used to determine the critical load of the fibre beams. These two engineering concepts were combined to form the equation for the proposed model. The derived equation is a function of the materials properties, geometric and physical parameters of the composite materials. The calculated stresses from the derived equation were compared with experimental data from technical and research papers. Good agreements shown in the results are encouraging and recommendations for future analysis with different modes of failure were also presented. This paper enables engineering designers to predict crushing stress in composite materials with confidence and makes their work more efficient and reliable

Cluster Extended Dynamical Mean Field Approach and Unconventional Superconductivity

The extended dynamical mean field theory has played an important role in the study of quantum phase transitions in heavy fermion systems. In order to incorporate the physics of unconventional superconductivity, we develop a cluster version of the extended dynamical mean field theory. In this approach, we show how magnetic order and superconductivity develop as a result of inter-site spin exchange interactions, and analyze in some detail the form of correlation functions. We also discuss the methods that can be used to solve the dynamical equations associated with this approach. Finally, we consider different settings in which our approach can be applied, including the periodic Anderson model for heavy fermion systems.Comment: 15 pages, 2 figures, Replaced with published versio

Model Supplay Chain Management dan Perancangan Aplikasi E-SCM pada PT Indofood Sukses Makmur Tbk Bogasari Flour Mills Division

The purpose of this study is to analyze company business process by determining the appropriate model of supply chain at PT Indofood Sukses Makmur Bogasari and designing the e-SCM system that aims to facilitate the flow of information and products to the company, ranging from suppliers to customers. Research used Porter's Five Forces analysis, value network analysis, order fulfillment based on the concept of decoupling point, EOQ (Economic Order Quantity) inventory model, and the method of designing an e-SCM system with Object Oriented Analysis Design (OOAD). The results of Porter's Five Forces analysis show that bargaining power of suppliers and competition among similar companies had a strong tendency, while bargaining power of customers, new competitors, and product substitution had a weak tendency in the external environment. In addition, the value chain analysis results show the condition of the company's internal information flows were substandard, especially in the upstream of the business process in the company. Based on the concept of decoupling point, MTS was more appropriate to Bogasari in response to consumer demand. Furthermore, this study also proposed EOQ inventory model so that the company can manage inventory and order better as well as overcome some of the problems such as the uncertainty in the inventory levels of consumer demand and limited raw materials from suppliers. The e-SCM online system application designed with Object Oriented Analysis Design (OOAD) is expected to facilitate the flow of information and to integrate its customers and agents in supporting company business process, so the information between suppliers and customers becomes well integrated

A Critical Examination to the Unitarized ππ\pi\pi Scattering Chiral Amplitudes

We discuss the Pad\'e approximation to the $\pi\pi$ scattering amplitudes in 1--loop chiral perturbation theory. The approximation restores unitarity and can reproduce the correct resonance poles, but the approximation violates crossing symmetry and produce spurious poles on the complex $s$ plane and therefore plagues its predictions on physical quantities at quantitative level. However we find that one virtual state in the IJ=20 channel may have physical relevance.Comment: 13 pages + 4 eps figures submit to Commun. Theor. Phy

Perbedaan Persepsi Mahasiswa Senior dan Junior Mengenai Profesi Akuntan pada Program S1 di Universitas Katolik Widya Mandala Surabaya

Accounting profession is work that has to be done in a professional and great responsibility towards the public,so that every student who will pursue this work should have the right attitudes and perceptions of the accounting profession. Therefore, when students still in the university they need to be taught to has a positive perception of accounting profession. This research used comparative with hypothesis testing aims to provide empirical evidence on differences in perceptions between senior and junior students of the accounting profession. The samples consist of senior students who have passed all internal and external courses (class of 2007 and 2008) and junior students who have passed the semester 1 (class of 2009 and 2010). The numbers of samples used by proportionate random sampling are 72 samples from senior students and 102 samples from junior students. The tool used is questionaire that contain list of statements. The results showed that there was no difference in perception between senior and junior students of the accounting profession in the bachelor of accounting at Widya Mandala Catholic University Surabaya

The cost of trauma operating theatre inefficiency.

The National Health Service (NHS) is currently facing a financial crisis with a projected deficit of £2billion by the end of financial year 2015/16. As operating rooms (OR) are one of the costliest components in secondary care, improving theatre efficiency should be at the forefront of efforts to improve health service efficiency. The objectives of this study were to characterize the causes of trauma OR delays and to estimate the cost of this inefficiency. A 1-month prospective single-centre study in St. Marys Hospital. Turnaround time (TT) was used as the surrogate parameter to measure theatre efficiency. Factors including patient age, ASA score and presence of surgical and anaesthetic consultant were evaluated to identify positive or negative associations with theatre delays. Inefficiency cost was calculated by multiplying the time wasted with staff capacity costs and opportunity costs, found to be £24.77/minute. The commonest causes for increased TT were delays in sending for patients (50%) and problems with patient transport to the OR (31%). 461 min of delay was observed in 12 days, equivalent to loss of £951.58/theatre/day. Non-statistically significant trends were seen between length of delays and advancing patient age, ASA score and absence of either a senior clinician or an anaesthetic consultant. Interestingly, the trend was not as strong for absence of an anaesthetic consultant. This study found delays in operating TT to represent a sizable cost, with potential efficiency savings based on TT of £347,327/theatre/year. Further study of a larger sample is warranted to better evaluate the identified trends

On Rotated CMV Operators and Orthogonal Polynomials on the Unit Circle

Split-step quantum walk operators can be expressed as a generalised version of CMV operators with complex transmission coefficients, which we call rotated CMV operators. Following the idea of Cantero, Moral and Velazquez's original construction of the original CMV operators from the theory of orthogonal polynomials on the unit circle (OPUC), we show that rotated CMV operators can be constructed similarly via a rotated version of OPUCs with respect to the same measure, and admit an analogous LM-factorisation as the original CMV operators. We also develop the rotated second kind polynomials corresponding to the rotated OPUCs. We then use the LM-factorisation of rotated alternate CMV operators to compute the Gesztesy-Zinchenko transfer matrices for rotated CMV operators.Comment: 43 pages, 4 table

Study of the Staebler-Wronski degradation effect in a-Si:H based p-i-n solar cell

Conversion of solar energy into electricity using environmentally safe and clean photovoltaic methods to supplement the ever increasing energy needs has been a cherished goal of many scientists and engineers around the world. Photovoltaic solar cells on the other hand, have been the power source for satellites ever since their introduction in the early sixties. For widespread terrestrial applications, however, the cost of photovoltaic systems must be reduced considerably. Much progress has been made in the recent past towards developing economically viable terrestrial systems, and the future looks highly promising. Thin film solar cells offer cost reductions mainly from their low processing cost, low material cost, and choice of low cost substrates. These are also very attractive for space applications because of their high power densities (power produced per kilogram of solar cell pay load) and high radiation resistance. Amorphous silicon based solar cells are amongst the top candidates for economically viable terrestrial and space based power generation. Despite very low federal funding during the eighties, amorphous silicon solar cell efficiencies have continually been improved - from a low 3 percent to over 13 percent now. Further improvements have been made by the use of multi-junction tandem solar cells. Efficiencies close to 15 percent have been achieved in several labs. In order to be competitive with fossil fuel generated electricity, it is believed that module efficiency of 15 percent or cell efficiency of 20 percent is required. Thus, further improvements in cell performance is imperative. One major problem that was discovered almost 15 years ago in amorphous silicon devices is the well known Staebler-Wronski Effect. Efficiency of amorphous silicon solar cells was found to degrade upon exposure to sunlight. Until now their is no consensus among the scientists on the mechanism for this degradation. Efficiency may degrade anywhere from 10 percent to almost 50 percent within the first few months of operation. In order to improve solar cell efficiencies, it is clear that the cause or causes of such degradation must be found and the processing conditions altered to minimize the loss in efficiency. This project was initiated in 1987 to investigate a possible link between metallic impurities, in particular, Ag, and this degradation. Such a link was established by one of the NASA scientists for the light induced degradation of n+/p crystalline silicon solar cells