Introduction to Production: Philosophies, Flow, and Analysis

Production is a fundamental societal and economic activity. Production has to do with the transformation of raw materials into useful objects and includes the knowledge to complete the transformation effectively. Thus, production is a board topic ranging from philosophies about how to approach production such as lean and quick response manufacturing, how to organize production facilities, how to analyze production operations, how to control the flow of materials during production, the devices used to move materials within a facility, and strategies for coordinating multiple production facilities. An integrated introduction to production is presented in a set of learning modules. In significant part, these learning modules are based on over 20 years of interactions with the professional production community in the West Michigan region where Grand Rapids and Holland are the principal cities. This community consists almost exclusively of small and medium size companies engaged primarily in high mix, low volume manufacturing. Students in the Bachelor of Science in Engineering and Master of Science in Engineering programs at Grand Valley State University often work in production for these companies. Thus, interactions are facilitated particularly though master’s degree capstone projects, several of which are referenced in the learning modules. The learning modules are well-grounded in established production concepts. Emphasis is placed on proven procedures such as systematic layout planning, factory physics, various production flow control techniques such as kanban and POLCA, and discrete event simulation. Professional practice is a focus of the learning modules. Material from processional groups such as the Lean Enterprise Institute and the Material Handling Institute (MHI) is integrated. The opportunity to read and discuss professional publications presenting production improvement projects is provided. Students are referred to professional videos and web sites throughout the learning modules. All materials provided are referenced are open access and free of charge. When downloading the main file, it is important to also download and use the Main File Support as it contains supplemental materials.https://scholarworks.gvsu.edu/books/1022/thumbnail.jp

Evaluation of Public and Private Risk Management Alternatives on Agricultural Producers in Southwest Oklahoma

Agricultural Economic

Open source solution approaches to a class of stochastic supply chain problems

This research proposes a variety of solution approaches to a class of stochastic supply chain problems, with normally distributed demand in a certain period of time in the future. These problems aim to provide the decisions regarding the production levels; supplier selection for raw materials; and optimal order quantity. The typical problem could be formulated as a mixed integer nonlinear program model, and the objective function for maximizing the expected profit is expressed in an integral format. In order to solve the problem, an open source solution package BONMIN is first employed to get the exact optimum result for small scale instances; then according to the specific feature of the problem a tailored nonlinear branch and bound framework is developed for larger scale problems through the introduction of triangular approximation approach and an iterative algorithm. Both open source solvers and commercial solvers are employed to solve the inner problem, and the results to larger scale problems demonstrate the competency of introduced approaches. In addition, two small heuristics are also introduced and the selected results are reported

Numerical methods for queues with shared service

A queueing system is a mathematical abstraction of a situation where elements, called customers, arrive in a system and wait until they receive some kind of service. Queueing systems are omnipresent in real life. Prime examples include people waiting at a counter to be served, airplanes waiting to take off, traffic jams during rush hour etc. Queueing theory is the mathematical study of queueing phenomena. As often neither the arrival instants of the customers nor their service times are known in advance, queueing theory most often assumes that these processes are random variables. The queueing process itself is then a stochastic process and most often also a Markov process, provided a proper description of the state of the queueing process is introduced. This dissertation investigates numerical methods for a particular type of Markovian queueing systems, namely queueing systems with shared service. These queueing systems differ from traditional queueing systems in that there is simultaneous service of the head-of-line customers of all queues and in that there is no service if there are no customers in one of the queues. The absence of service whenever one of the queues is empty yields particular dynamics which are not found in traditional queueing systems. These queueing systems with shared service are not only beautiful mathematical objects in their own right, but are also motivated by an extensive range of applications. The original motivation for studying queueing systems with shared service came from a particular process in inventory management called kitting. A kitting process collects the necessary parts for an end product in a box prior to sending it to the assembly area. The parts and their inventories being the customers and queues, we get ``shared service'' as kitting cannot proceed if some parts are absent. Still in the area of inventory management, the decoupling inventory of a hybrid make-to-stock/make-to-order system exhibits shared service. The production process prior to the decoupling inventory is make-to-stock and driven by demand forecasts. In contrast, the production process after the decoupling inventory is make-to-order and driven by actual demand as items from the decoupling inventory are customised according to customer specifications. At the decoupling point, the decoupling inventory is complemented with a queue of outstanding orders. As customisation only starts when the decoupling inventory is nonempty and there is at least one order, there is again shared service. Moving to applications in telecommunications, shared service applies to energy harvesting sensor nodes. Such a sensor node scavenges energy from its environment to meet its energy expenditure or to prolong its lifetime. A rechargeable battery operates very much like a queue, customers being discretised as chunks of energy. As a sensor node requires both sensed data and energy for transmission, shared service can again be identified. In the Markovian framework, "solving" a queueing system corresponds to finding the steady-state solution of the Markov process that describes the queueing system at hand. Indeed, most performance measures of interest of the queueing system can be expressed in terms of the steady-state solution of the underlying Markov process. For a finite ergodic Markov process, the steady-state solution is the unique solution of $N-1$ balance equations complemented with the normalisation condition, $N$ being the size of the state space. For the queueing systems with shared service, the size of the state space of the Markov processes grows exponentially with the number of queues involved. Hence, even if only a moderate number of queues are considered, the size of the state space is huge. This is the state-space explosion problem. As direct solution methods for such Markov processes are computationally infeasible, this dissertation aims at exploiting structural properties of the Markov processes, as to speed up computation of the steady-state solution. The first property that can be exploited is sparsity of the generator matrix of the Markov process. Indeed, the number of events that can occur in any state --- or equivalently, the number of transitions to other states --- is far smaller than the size of the state space. This means that the generator matrix of the Markov process is mainly filled with zeroes. Iterative methods for sparse linear systems --- in particular the Krylov subspace solver GMRES --- were found to be computationally efficient for studying kitting processes only if the number of queues is limited. For more queues (or a larger state space), the methods cannot calculate the steady-state performance measures sufficiently fast. The applications related to the decoupling inventory and the energy harvesting sensor node involve only two queues. In this case, the generator matrix exhibits a homogene block-tridiagonal structure. Such Markov processes can be solved efficiently by means of matrix-geometric methods, both in the case that the process has finite size and --- even more efficiently --- in the case that it has an infinite size and a finite block size. Neither of the former exact solution methods allows for investigating systems with many queues. Therefore we developed an approximate numerical solution method, based on Maclaurin series expansions. Rather than focussing on structural properties of the Markov process for any parameter setting, the series expansion technique exploits structural properties of the Markov process when some parameter is sent to zero. For the queues with shared exponential service and the service rate sent to zero, the resulting process has a single absorbing state and the states can be ordered such that the generator matrix is upper-diagonal. In this case, the solution at zero is trivial and the calculation of the higher order terms in the series expansion around zero has a computational complexity proportional to the size of the state space. This is a case of regular perturbation of the parameter and contrasts to singular perturbation which is applied when the service times of the kitting process are phase-type distributed. For singular perturbation, the Markov process has no unique steady-state solution when the parameter is sent to zero. However, similar techniques still apply, albeit at a higher computational cost. Finally we note that the numerical series expansion technique is not limited to evaluating queues with shared service. Resembling shared queueing systems in that a Markov process with multidimensional state space is considered, it is shown that the regular series expansion technique can be applied on an epidemic model for opinion propagation in a social network. Interestingly, we find that the series expansion technique complements the usual fluid approach of the epidemic literature

A Bioeconomic Analysis of Sea Scallop (Placopecten Magellanicus) Aquaculture in the Gulf of Maine

Aquaculture is the fastest growing food production sector in the world. In the Northwest Atlantic, interest in Sea Scallop (Placopecten magellanicus) (hereafter scallop) aquaculture has grown rapidly in the last decade. In the U.S., scallops support a ~$1 billion USD industry with nearly$500 million coming from imports. By comparison, the U.S. exports only ~$139 million USD of scallops annually. This substantial trade imbalance and strong domestic demand has created an opportunity for a farmed product to capture a share of the market. However, technical, regulatory, and, perhaps most importantly, economic challenges have stifled the growth of scallop aquaculture in the Northwest Atlantic. We performed semi-structured interviews (n = 7) with the majority of scallop farmers in Maine, USA to parameterize a scallop aquaculture bioeconomic model. To identify production bottlenecks and assess the influence of various biological and market variables on farm-scale success, we conducted financial simulations for farms of various sizes targeting either live whole scallops or the traditionally consumed shucked adductor muscle meat . The end product (“whole” or “meat”) had a large influence on the profitability of farms. For example, farms selling \u3e 200,000 whole scallops year-1 were profitable. However, all farms selling shucked meats generated negative returns. Labor made up the greatest portion of costs in all model simulations and increased linearly with farm size, representing a significant bottleneck. Farm value was most sensitive to changes in market price, time to market, and annual sales. Businesses selling whole scallops can potentially be successful, but regulatory or labor mechanization issues could hinder further expansion of the industry. Our analysis suggests four strategies to increase farmed scallop production in the Northwest Atlantic: (1) develop methods to mechanize low density net culture, (2) optimize net stocking densities, (3) build site selection tools that decrease time to market, and (4) invest in end-markets and biotoxin testing for whole scallops. Diversifying the shellfish aquaculture sector by increasing the viability of scallop aquaculture has the potential to play a key role in increasing the economic resilience of coastal communities

Novi profil gradskih luka u razvoju nautičkog turizma

Maritime ports are an integral part of the large towns, their most attractive, and at the same time, their most profitable area. The development of ports in Croatia and in the Mediterranean has proceeded alongside the development of maritime towns. Their age parallels the age of the towns. Throughout history, town ports have changed their economic role and profile adapting to the needs of the market and towns. The development of nautical tourism has placed great pressure on the old ports changing their existing profile. Over the centuries, town ports of large and medium-size towns have performed the function of maritime traffic, transportation of persons and cargo, and trade. For nautical tourism to achieve good development results and a consistently high development rate, it is necessary to change the classical profile of town ports by transforming them from maritime ports into ports for nautical tourism. What types of changes are involved? What do these changes bring? The answers to these questions and others shall be given in this article.Pomorske luke dio su velikih gradova i njihova najatraktivnija i najvrjednija područja. Razvoj luka u Hrvatskoj i na Mediteranu išao je u korak s razvojem gradova na obali. Njihova starost jednaka je starosti grada. Tijekom povijesti, gradske su luke mijenjale svoju gospodarsku ulogu i profil, prilagođavajući se potrebama tržišta i grada. Razvoj nautičkog turizma izvršio je na stare luke veliki pritisak, u smislu promjene njihovog postojećeg profila. Gradske luke velikih i srednje velikih gradova vjekovima su u funkciji pomorskog prometa, prijevoza ljudi i tereta i trgovine. Dobri razvojni rezultat nautičkog turizma i kontinuirano visoke razvojne stope, zahtijevaju promjenu klasičnog profila gradskih luka na način da se luke za pomorski promet transformiraju u luke nautičkog turizma. O kakvim se promjenama radi? Što donose te promjene? Na ova i druga pitanja nastoji se odgovoriti u ovom tekstu