Investigation of the diesel consumption for trucks at an overburden stripping area by SPC study

This study examined whether diesel consumption used by trucks at a stripping area is controlled or not. The factors affecting diesel consumption were also investigated and some necessary solutions were presented. Diesel consumption was observed with the aid of control graphs. Abnormal situations in the diesel consumption were explored by means of Shewhart control graphs. The factors which are out of control were also presented in a cause–effect diagram, and suggestions for improvement were proposed. It has been determined that the main effect of the diesel consumption is the daily run number of the trucks. The main factors affecting the daily run number were also investigated.     

基于总量控制的工业领域能源分配双层规划模型

在工业领域实施能源消费总量控制是节能管理工作的趋势,可以在约束能源消费总量的同时带动工业能耗强度下降,并进一步促进社会综合能耗强度的下降。在此背景下,能源的科学分配尤其重要,并具有明显的层次性。本文针对此问题构建了工业领域能源分配双层规划模型,上层为多目标规划,描述上级政府行为,以社会的经济性、协调性和可持续发展性为目标,以在下级之间的合理调配为约束条件,下层为目标规划,描述能源在下级行业之间的配置优先权。根据该模型的决策特点,给出了基于决策者偏好的迭代算法。算例说明该分配方法可以有效倒逼各级地方政府"转方式、调结构",科学引导高耗能行业的发展。     

企业进入权、组织控制与跨国公司专用性投资激励

论文从国际生产组织控制视角,将Rajan和Zingales^[1]进入权思想融入国际生产与贸易模型中,研究跨国公司专用性投资激励问题。研究发现,在进入权的机会控制和数量调整机制作用下,跨国公司通过限制进入、替代竞争来激发当地供应商做出事前定制投资、分摊投资和事后最优专用性投资,确保获取合意投入品和预期最大化利润。当前,政府要引导外向企业致力于微观企业主体的制度建设和组织能力培养,构建起中国国际生产网络及其组织机制,为推进对外直接投资和企业国际化经营提供微观保障。     

Supplies from developing countries: Optimal order quantities under loss risks

When raw material suppliers of a global supply chain are situated in developing countries, not only will there be long lead times but there could also be a possibility of material losses in transit. The magnitude of the losses will be uncertain and can be significant. We consider the optimization of order quantity decisions in such situations. The long lead times imply that we need to take into account the uncertainty in finished goods demands for which the raw materials are to be ordered. The order quantities have to be optimized carefully as they determine the “real options” that become available later in production plans. Using data from the plywood industry and using stochastic programming we demonstrate a method for solving such problems. The method combines simulation and optimization. An interesting observation we make is that the optimal order quantity of a material need not be monotonic in expected loss of that material. In addition, we offer explanations as to why the expected loss need not be monotonic.     

Inventory management with variable lead-time dependent procurement cost

A reduction in the inventory replenishment lead-time allows reducing safety stock requirements and improving customer service. However, it might be accompanied by increased procurement costs because of premium charges imposed by suppliers, or higher transportation costs. This paper studies a single-stage variable lead-time inventory system with lead-time dependent procurement cost. Selection of the lead-time value represents finding the trade-off between benefits of lead-time reduction and increase in the procurement cost. A model for joint optimization of inventory and procurement costs is developed. Numerical studies are conducted to identify conditions under which lead-time reduction is favorable compared to procuring at the lowest cost.     

Open Source Development with a Commercial Complementary Product or Service

We examine optimal control decisions regarding pricing, network size, and hiring strategy in the context of open source software development. Opening the source code to a software product often implies that consumers would not pay for the software product itself. However, revenues may be generated from complementary products. A software firm may be willing to open the source code to its software if it stands to build a network for its complementary products. The rapid network growth is doubly crucial in open source development, in which the users of the firm's products are also contributors of code that translates to future quality improvements. To determine whether or not to open the source, a software firm must jointly optimize prices for its various products while simultaneously managing its product quality, network size, and employment strategy. Whether or not potential gains in product quality, network size, and labor savings are sufficient to justify opening the source code depends on product and demand characteristics of both the software and the complementary product, as well as on the cost and productivity of in‐house developers relative to open source contributors. This paper investigates these crucial elements to allow firms to reach the optimal decision in choosing between the open and closed source models.     

Order Progress Information: Improved Dynamic Emergency Ordering Policies

Technologies such as radio‐frequency identification and global positioning systems can provide improved real‐time tracking information for products and replenishment orders along the supply chain. We call this type of visibility order progress information. In this paper, we investigate how order progress information can be used to improve inventory replenishment decisions. To this end, we examine a retailer facing a stochastic lead time for order fulfillment. We characterize a replenishment policy that is based on the classical (Q, R) policy and that allows for releasing emergency orders in response to the order progress information. We show that the optimal structure of this policy is given by a sequence of threshold values dependent on order progress information. In a numerical study we evaluate the cost savings due to this improved replenishment policy.     

Value of Sharing Production Yield Information in a Serial Supply Chain

New developments in corporate information technology such as enterprise resource planning systems have significantly increased the flow of information among members of supply chains. However, the benefits of sharing information can vary depending on the supply chain structure and its operational characteristics. Most of the existing research has studied the impact of sharing downstream information (e.g., a manufacturer sharing information with its suppliers). We evaluate the benefits of sharing upstream yield information (e.g., a supplier sharing information with the manufacturer) in a two‐stage serial supply chain in which the supplier has multiple internal processes and is faced with uncertain output due to yield losses. We are interested in determining when the sharing of the supplier's information is most beneficial to the manufacturer. After proposing an order‐up‐to type heuristic policy, we perform a detailed computational study and observe that this information is most beneficial when the supplier's yield variance is high and when end‐customer demand variance is low. We also find that the manufacturer's backorder‐to‐holding cost ratio has little, if any, impact on the usefulness of information.     

Controlling Access to Sick Leave Programmes: Practices of Physicians in the Netherlands

Policymakers in industrialized countries attempt to contain the costs of sick leave and disability schemes by limiting access to include medically proven cases only. However, a person's incapacity to work cannot be fully deduced by referring to his or her medical condition. It is the question whether using more restrictive eligibility criteria that focus on medical evidence actually reduces the number of benefit recipients and makes access to employee benefit arrangements fairer. This ethnographic study shows that physicians working in Dutch illness certification practices use alternative methods to restrict access to sick leave programmes. Doctors do not control their clients in a restrictive sense of the word. Rather, they exercise control over their clients by inciting them to internalize norms about being active and responsible. While we do not claim that this is good per se, we do contend that this control style may have some advantages over and above more restrictive control mechanisms. Elaborating on policy that supports this alternative notion of control, therefore, seems worthwhile.     

On the significance of social control: Treatment‐entry pressures,self‐choice and alcohol and drug dependence criteria one year after treatment

Storbjörk J. On the significance of social control: treatment‐entry pressures, self‐choice and alcohol and drug dependence criteria one year after treatment This article explores how self‐choice and treatment‐entry pressures are associated with one‐year treatment outcome (dependence symptoms, 0–6, 12 months) among alcohol and drug misusers, respectively. Informal pressures (from family and friends), formal pressures (related to work, healthcare, social services, social allowances, child custody) and legal pressures (related to the police, criminal justice system, compulsory treatment) were analysed. A sample (N= 1,210) representative of the addiction treatment system of Stockholm County was interviewed when starting a new treatment episode and after one year. Regression analyses indicated that self‐choice and pressures are associated with outcome among alcohol misusers but not among drug misusers when controlling for background factors and severity. Self‐choice (without pressures) correlated with a good outcome (a lower number of dependence criteria). Pressures were generally associated with poorer outcome. Alcohol misusers who had experienced threats regarding child custody did better in comparison with those not experiencing such pressure. The difference in results by drug type and implications were discussed.