Li Zheng

Cycle time reduction in assembly and test manufacturing factories: A KPI driven methodology

In this paper we will introduce a new cycle time performance tracking matrix derived from the factory physics queuing model. We will explore a systematic way to structure the hierarchical cycle time key performance indicators (KPI) framework and also to define the right owner to improve those measurements. We will extend the discussion to some control and improvement methods, in particular, CONWIP release control management, a first in first out (FIFO) dispatching automation tool and the use of value stream mapping (VSM) to reduce factory variability. These tools and methods lead to great benefits to the factory cost saving.

A MILP-based batch scheduling for two-stage hybrid flowshop with sequence-dependent setups in semiconductor assembly and test manufacturing

In semiconductor assembly and test manufacturing, it is critical to optimize the scheduling of constraint stations to improve the system performance. This paper presents a continuous-time mixed-integer linear programming (MILP) model for the short-term batch scheduling with sequence-dependent setups in semiconductor assembly and test manufacturing to minimize the total completion time of the products. We formulate the problem of scheduling the two constraint stations and develop the MILP-based heuristic scheduling framework. The heuristic algorithm pre-determines the batch size according to the practical business rules and allocates the least flexible machines to the qualified high volume products. The system implementation at a semiconductor ATM factory demonstrates a significant reduction in total completion time compared to the traditional scheduling approach.

Reliability analysis of a novel structure in an automatic sorting system

Reliability and safety is very important for logistic equipments especially sorting system. In this paper a novel structure of automatic sorting system is designed based on Double 2 vote 2 Redundancy (D2V2R) structure. By using this structure, the reliability of the system is enhanced comparing with traditional simplex system and duplex system. Analytical results based on basic reliability analyzing theory are also given for systems using these structures.

Chinese consumer responses to carbon labeling: evidence from experimental auctions

With the growing anxiety over global warming, some groups have advocated the mandatory carbon labeling of products, whereas other groups have opposed such labeling. How consumers respond to carbon labels is a key question with important implications for both policy-makers and managers. Using a random nth-price auction experiment together with a questionnaire, we systematically examined the extent to which Chinese consumers care about environmental impacts and how their willingness to pay (WTP) is influenced by carbon labels. We have determined that WTP significantly increases for products with added carbon labels and decreases when the carbon emissions of a product increase. This response to carbon information disclosure is influenced by factors such as the gender and awareness of environmental pollution by the consumer. This study offers valuable insights to policy-makers and managers for carbon labeling promotion and product positioning.

A new practical conformance testing method based on standard

The overall framework and principles of conformance and testing have been described by the series standards of ISO/IEC 9646. However, those standards fail to present a feasible tool to execute the testing. In this paper, a new practical conformance testing method based on standard is presented. First, the system under test(SUT) answers to the Implementation Conformance Statement (ICS) proforma designed by the testing laboratory based on the basis standard, then the corresponding use cases for testing could be settled based on the answers and the testing proforma could be designed accordingly, establishing a practical mechanism to instantiate the Executable Test Suite (ETS) with the Abstract Test Suite (ATS). Additionally, a number of experiments were performed to certify the validity of our method. The results indicate that the method can be popularized in the field of standardization.

Simplification of decision making matrix in fuzzy multiple attribute decision making

In the multiple attribute decision making, the computational intensity of problems quickly increases with the number of attributes increases. In this paper, we will introduce the simplification theory and technology of decision matrix in fuzzy multiple attribute decision making, and propose an attribute reduction algorithm. The purpose of this algorithm is to find all of the simplest order-preserving attribute subsets and the order-preserving attribute core of the corresponding multiple attribute decision making problem. One of the simplest order-preserving attribute subsets will be exploited as a substitute of the original attribute set. Thus the original multiple attribute decision making problem could be simplified and unnecessary cost related to redundant attributes could be saved. Finally, an illustrative numerical example is given to demonstrate our approach. And through this example, a dissimilarity between the attribute reduction in decision making and the knowledge reduction in rough set theory is discovered.

Spatial-based decomposition approach for the crude scheduling problem of a refinery with multiple ports and long-distance pipelines

This work addresses the large-scale crude scheduling problem of a real case refinery importing various types of crude oil from two ports via long-distance pipelines. We employ a spatial-based decomposition approach to construct a two-stage model of the practical refinery operations. During the first stage, the refinery plant is treated as a single aggregated demand node to simplify the port sub-problem. Specific receiving and charging operations of the plant sub-problem are then determined in the second stage. While the overall model of the refinery is difficult to solve, the decomposition approach could obtain satisfactory and flexible scheduling results with much less computational efforts.

The design of cooperative planning processes in railway bureaus based on roles, activities and time sequences

The successful design of complex cooperative planning process on daily dispatching plan allows multi dispatchers in railway bureaus to cooperatively make daily dispatching plans. This is helpful to improve the accuracy of daily dispatching plan and further to improve the overall efficiency of railway transportation in China. And building the cooperative planning process is also important for the configuration of the transporting dispatching management information system (TDMS 4.0) used in railway bureaus in China. However, designing such a process is very difficult, considering the complexity of the process. In this paper, a new design method based on roles, activities and time sequences is provided. Finally, the new cooperative planning process is constructed by re-arranging the time sequences relationships among roles, activities in the current process.

A note to TOPSIS method in MADM problems under fuzzy environment

TOPSIS method has been widely used to solve various multiple attribute decision making and multiple criteria decision making problems since Hwang and Yoon first introduced it in 1981. The ranking results of TOPSIS are proved to be relatively convincing in many practical areas. However, in recent research we find that the traditional fuzzy TOPSIS method could not distinguish all of the alternatives in some circumstances. As stated later in this paper, several counter examples in triangular fuzzy number format will be demonstrated, where the fuzzy TOPSIS method fails to give alternatives respective rankings. And the reason for that phenomenon will be further discussed. Then a revised procedure is suggested in order to fully differentiate all of the alternatives. Finally a numerical example is given so as to testify the revised procedure.

Performance evaluation of a multi-product system with setups and dynamic scheduling policies

The manufacturing factories of electronic products such as micro-processors, TFT-LCD monitors and LED usually have multi-product production lines with sequence-dependent setups and high uncertainties. Dynamic scheduling policies which consider the state of the entire system are needed in such production lines. In this paper, a continuous time Markovian model is developed to evaluate the performance of a three-product production system with sequence-dependent setup times and dynamic scheduling policies. Three policies are studied in numerical experiments and some managerial insights are proposed.