Rigorous constraints on the matrix elements of the energy-momentum tensor

The structure of the matrix elements of the energy-momentum tensor play an important role in determining the properties of the form factors $A(q^{2})$, $B(q^{2})$ and $C(q^{2})$ which appear in the Lorentz covariant decomposition of the matrix elements. In this paper we apply a rigorous frame-independent distributional-matching approach to the matrix elements of the Poincar\'{e} generators in order to derive constraints on these form factors as $q \rightarrow 0$. In contrast to the literature, we explicitly demonstrate that the vanishing of the anomalous gravitomagnetic moment $B(0)$ and the condition $A(0)=1$ are independent of one another, and that these constraints are not related to the specific properties or conservation of the individual Poincar\'{e} generators themselves, but are in fact a consequence of the physical on-shell requirement of the states in the matrix elements and the manner in which these states transform under Poincar\'{e} transformations.Comment: 11 pages; v2: additional comments added, matches published versio

Academic Dress in China from 1994 to 2011

Introduction: This article reports the development of academic dress in China from the year 1994 to 2011. China has two self-governing special administrative regions (Hong Kong and Macau), and claims sovereignty over Taiwan; these three areas are not included in this study because the laws of China do not apply directly in them. As a result, academic dress in these areas has been influenced by different parts of the world

Finite Domain Bounds Consistency Revisited

A widely adopted approach to solving constraint satisfaction problems combines systematic tree search with constraint propagation for pruning the search space. Constraint propagation is performed by propagators implementing a certain notion of consistency. Bounds consistency is the method of choice for building propagators for arithmetic constraints and several global constraints in the finite integer domain. However, there has been some confusion in the definition of bounds consistency. In this paper we clarify the differences and similarities among the three commonly used notions of bounds consistency.Comment: 12 page

Web-site teaching: analysis of its future development

Web-site teaching has become increasingly popular in universities and continuous education. This article discusses the advantages of web-site teaching. In particular the effect of web-site teaching on life-long learning is examined. It is concluded that web-site teaching will have large scope of future development and that education institutions especially those aiming at providing life-long learning to mature working people will need to start preparing for this revolutionary change in method of teaching

Optimal production cycle time for multi-item FPR model with rework and multi-shipment policy

This paper determines the optimal common production cycle time for a multi-item finite production rate (FPR) model with rework and multi-shipment policy. The classic FPR model considers production planning for a single product with perfect quality production and a continuous issuing policy. However, in real life production environments, vendors often plan to produce multiple products in turn on a single machine in order to maximize the machine utilization. Also, due to various uncontrollable factors, generation of nonconforming items in any given production run is inevitable. It is also common for vendors to adopt multiple/periodic delivery policy for distributing their finished goods to customers. In this study, it is assumed that all nonconforming items can be reworked and repaired in the same cycle when regular production ends at additional cost per each reworked item. Our objective is to determine the optimal common production cycle time that minimizes the long-run average cost per unit time and to study the effect of rework on the optimal common cycle time for such a specific multi-item FPR model with rework and multi-shipment policy. Mathematical modeling is used, and the expected system cost for the proposed model is derived and proved to be convex. Finally, a closed-form optimal cycle time is obtained. A numerical example and sensitivity analysis is provided to show the practical use of our obtained results

Economic lot sizing with imperfect rework derived without derivatives

This paper presents an algebraic method for solving economic production quantity (EPQ) model with imperfect rework. Conventional method for deriving optimal lot size is by using differential calculus on the cost function with the need to prove optimality first. Recent articles proposed algebraic approach to the solution of classic economic order quantity (EOQ) and EPQ model without reference to the use of derivatives. This note extends them to an EPQ model taking into consideration an imperfect rework of defective items. We demonstrate that the optimal lot size and the expected production-inventory cost for such a realistic EPQ model can be derived without derivatives

Economic lot sizing with imperfect rework derived without derivatives

This paper presents an algebraic method for solving economic production quantity (EPQ) model with imperfect rework. Conventional method for deriving optimal lot size is by using differential calculus on the cost function with the need to prove optimality first. Recent articles proposed algebraic approach to the solution of classic economic order quantity (EOQ) and EPQ model without reference to the use of derivatives. This note extends them to an EPQ model taking into consideration an imperfect rework of defective items. We demonstrate that the optimal lot size and the expected production-inventory cost for such a realistic EPQ model can be derived without derivatives