Measurement of the Proton Spin Structure Function g1p with a Pure Hydrogen Target

A measurement of the proton spin structure function g1p(x,Q^2) in deep-inelastic scattering is presented. The data were taken with the 27.6 GeV longitudinally polarised positron beam at HERA incident on a longitudinally polarised pure hydrogen gas target internal to the storage ring. The kinematic range is 0.021<x<0.85 and 0.8 GeV^2<Q^2<20 GeV^2. The integral Int_{0.021}^{0.85} g1p(x)dx evaluated at Q0^2 of 2.5 GeV^2 is 0.122+/-0.003(stat.)+/-0.010(syst.).Comment: 7 pages, 3 figures, 1 table, RevTeX late

A Search for Selectrons and Squarks at HERA

Data from electron-proton collisions at a center-of-mass energy of 300 GeV are used for a search for selectrons and squarks within the framework of the minimal supersymmetric model. The decays of selectrons and squarks into the lightest supersymmetric particle lead to final states with an electron and hadrons accompanied by large missing energy and transverse momentum. No signal is found and new bounds on the existence of these particles are derived. At 95% confidence level the excluded region extends to 65 GeV for selectron and squark masses, and to 40 GeV for the mass of the lightest supersymmetric particle.Comment: 13 pages, latex, 6 Figure

Integrating Production Planning and Control: Toward a Simple Model for Capacitated ERP

Despite great advances in enterprise management software during the past several decades, there remains a significant opportunity in the design of production and material planning systems. After a discussion of a major technical flaw in enterprise resource planning/material requirement planning (ERP/MRP) systems, we outline advanced planning in literature and selected software products, with focus on the notion of planned lead times and limited capacity. We then describe ‘Capacitated ERP’–a simple variation of production and material requirements planning of components that takes into account resource capacity before exploding requirements to lower level components (upstream supply tiers). The model is presented with an example at the component planning level in a declarative (as opposed to a procedural) format, consequently facilitating implementation in a spreadsheet environment, which is often used by small and midsized companies. An outline showing how to integrate this component into a typical Supply Chain Management-software environment for such firms is included. Finally, we generate initial insights gained from our proposed method applied to an aircraft engine supplier

Developing Undergraduate Student Research Experiences in Operations Management

In search of pedagogical strategies to raise undergraduate business education to a new level, the Carnegie\u27s Boyer Commission Report (1998) recommends “to make research-based learning the standard.” In other countries, this is already the norm. In Germany, for example, business students typically prepare several theses as a formal part of their studies. Also in science and engineering, research participation is an important step in undergraduate student development and is hence highly promoted by the National Science Foundation (NSF). In 2006, the NSF devoted $33 million to corresponding programs. Benefits are highlighted in numerous pedagogical articles––see, for example, Chang (2005). Unlike science and engineering, business student involvement in research activities in U.S. schools has been traditionally restricted to graduates (master\u27s, PhD). A notable exception can be found at the University of Dayton (UD), Ohio. Here, we offer an undergraduate research experience for all students of Operations Management. It constitutes roughly 35% of the semester schedule of Supply Chain Management Strategies, a final core course for students in the fourth year. Circa 40 working hours are allocated for the active research experience for each student. The goal of the program is to infuse an attitude of lifelong learning, to sharpen students\u27 objectivity, to enhance their ability to search and filter relevant information, and to improve their writing and oral presentation skills. Students might be motivated by the following tangible benefits. The program helps them specialize “just-in-time,” that is, weeks before graduating, on a topic of their interest and choice, respectively. As the final presentations are conducted in a professional setting, interested companies can contact students directly for job opportunities. Research projects serve as a unique selling point in a student\u27s curriculum vitae. For example, a recent undergraduate won the prestigious American Production and Inventory Control Society (APICS) national student paper competition for his project under this program

Using a Supply Chain Game to Effect Problem-Based Learning in an Undergraduate Operations Management Program

Problem-based learning (PBL), first applied in the 1960s in the domain of medicine, is now underway in a number of leading U.S. business schools. We combine the case-oriented PBL approach with a competitive game in “Supply Chain Management Strategies” (OPS 480), a course for senior-level students. The PBL component constitutes roughly 40% of the semester schedule. It has been gradually refined over several years. By itself, the PBL is a highly effective pedagogical technique, but what a game offers is this and more. Its competitive nature adds motivation—our undergraduates see the impact of their decisions instantaneously in cash flow balance and overall team standing. The course is completed with an array of other established activities. Proponents of PBL claim its advantage to be that as learning is goal oriented, the knowledge acquisition is enhanced and the learning is deeper (e.g., see Faria & Weffington, 2005). Students get hands-on experience in various topics, some of which were covered in previous courses and others the students learn about in the current semester. In German-speaking countries, PBL is considered to be the most important pedagogical innovation (Markowitsch, Messerer, & Prokopp, 2004, p. 90). For a review of PBL in business education, see, for example, Milter and Stinson (1995), Savery and Duffy (1996), and Zumbach (2003). For an earlier example of PBL in Operations Management, see Kanet and Barut (2003)

Dynamic Planned Safety Stocks in Supply Networks

Safety stocks are commonly used in inventory management for tactically planning against uncertainty in demand and/or supply. The usual approach is to plan a single safety stock value for the entire planning horizon. More advanced methods allow for dynamically updating this value. We introduce a new line of research in inventory management: the notion of planning time-phased safety stocks. We assert that planning a time-phased set of safety stocks over a planning horizon makes sense because larger safety stocks are appropriate in times of greater uncertainty while lower safety stocks are more appropriate when demand and/or supply are more predictable. Projecting a vector of safety stock values is necessary to assure upstream members in the supply network have advanced warning of changes. We perform an empirical study of U.S. industry, which demonstrates that significant savings can be achieved by employing dynamic planned safety stocks, confirming recent case study reports. We provide a simple optimisation model for the problem of minimising inventory given a vector of safety stock targets. We propose a computationally efficient solution procedure and demonstrate its implementation in an MRP/ERP system. We then illustrate an MRP/ERP planning system feature, which employs a dynamic planned safety stock module that supports a production planner by showing the inventory implications of safety stock plans