Ryota Akai

Mathematical model for simultaneous design of module commonalization and supply chain configuration toward global product family

Manufacturing today has become global in all aspects marketing, design, production, distribution, etc. While product family design has been an essential viewpoint for meeting the demand for product variety, its interaction with the issues of supply chain, market systems, etc. makes the meaning of product family both broad and more complicated. In this paper we call such situation ‘global product family,’ and first characterizes its components and complexity. Following this, we proposes a mathematical model for the simultaneous design problem of module commonalization strategies under the given product architecture and supply chain configuration through selection of manufacturing sites for module production, assembly and final distribution as an instance of the problems. In the model, the choice of modules and various sites are represented with 0-1 design variables with the volume of production and transportation represented with non-negative continuous design variables, and the objective defined on total cost. An optimization method is configured with a genetic algorithm and a simplex method for such a mixed integer programming problem. Some numerical case studies are included to determine the validity and promise of the developed mathematical model and algorithm. Finally, we conclude with some discussion of future work.

Experiment on battery-less sensor activation via multi-point wireless energy transmission

This paper presents an indoor experiment to verify the battery-less sensor activation via multi-point wireless energy transmission with carrier shift diversity which realizes seamless coverage extension of the sensor activation. The multi-point scheme is employed to overcome path-loss attenuation. The carrier shift diversity has been developed to achieve uniform coverage of power transmission by combating standing-wave problem caused by multi-point transmitters as well as multipath waves, while its effectiveness on activation of battery-less sensors has never been studied in real environments. In this paper, we develop prototype hardware of battery-less sensor and conduct an indoor experiment with the developed sensor node. The experimental results show that the coverage of single-point and simple multi-point wireless energy transmission are limited at 44% and 70% respectively, while that of the proposed multi-point wireless energy transmission with carrier shift diversity achieves 100% to activate the developed sensor node which consumes -4 dBm for a transmission period of 1s.

Product Family Deployment Through Optimal Resource Allocation Under Market System

A series of products, i.e. a product family is deployed for effectively and flexibly meeting with a variety of customer’s needs under a given product platform. Since such a deployment consumes various engineering resources and simultaneously brings profits gradually over the time sequence, when and how respective modules are designed and respective products are launched to the market must be rationally planed. Further, as a nature of product families, module commonalization accelerates the deployment but infuses some overheads on features and production cost. This paper investigates such a product family deployment problem under the optimal design viewpoint. After some general discussions, a mathematical model of dynamic design decisions is conditionally developed by integrating a combinatorial optimization technique for decision of module selection on commonalization and a market system model with discrete choice analysis and for describing the compromise among sequence of product rollout, arrangement of product lineup, required engineering resource, expected profit, etc. Then, the compromise among those factors is illustrated through the case study on a simplified deployment problem of circuit boards for digital television sets. Finally, an optimal planning approach for product family deployment and accompanied resource allocation is envisioned based on the developed model and findings from the case studies.Copyright

Design Method Selection Matrix for Facilitating Product Platform and Family Design

The aim of this research is to develop a method to manage product platform and family design methods and to select one appropriate for a specific design case. As the need for product platform has increased over the last 20 years, research within the area has led to the development of various methods that aim at evaluating a candidate of design. While sharing similar approach, different researchers have developed different methods that vary greatly in type, focus and complexity. Although their differences are considered a strong point of the theoretical field, the large variety can end up complicating the selection process, which will result in choosing less optimal methods for a specific design case. This paper proposes Design Method Selection Matrix (DMSM) that can help designers choose appropriate design methods. The underlying basis for the proposed DMSM is to determine methods appropriateness based on the availability of information, which is defined by the situation in which the evaluation takes place, as well as the importance of information, which is determined by the goal of the evaluation. The output of DMSM is a score for each of the identified methods that represent the appropriateness of the given method, based on the situation and goal(s) chosen by the designer. Suggestions are based on parameters that can easily be determined by designers without extensive experience within platform based product design. The case study demonstrates the effectiveness of DMSM.Copyright

Global Product Family Design: A Mathematical Model for Simultaneous Decision of Module Commonalization and Supply Chain Configuration

Today’s manufacturing has become global at all aspects of marketing, design, production, distribution, etc. While product family design has been an essential viewpoint for meeting with the demand for product variety, its meaning is becoming more broad and complicated with linking product design with issues on market systems, supply chain, etc. This paper calls such a design situation ‘global product family design,’ and firstly characterizes its components and complexity. Following them, this paper develops a mathematical model for the simultaneous decision problem of module commonalization strategies under the given product architecture and supply chain configuration through selection of manufacturing sites for module production, assembly and final distribution as an instance of the problems. This paper demonstrates some numerical case studies for ascertaining the validity and promise of the developed mathematical model with an optimization method configured with a genetic algorithm and a simplex method. Finally, it concludes with some discussion on future works.Copyright

Real-Time People Counting across Spatially Adjacent Non-overlapping Camera Views

Counting the number of people traveling across non- overlapping camera views generally requires all persons exiting any camera view to be re-identified when they re-enter one of its spatially adjacent camera views. For their accurate re-identification, the correspondence among the exits and entries of all persons should be established so that their total correspondence confidence is maximized. In order to realize the real-time people counting, we propose to find the shortest time window to observe both the exits and entries of all persons traveling within the time window adaptively to the current people traffic flow. Further, since closely related people often travel together, the re-identification can be performed to the foreground regions to re-identify groups of people. Since the groups of people can sometimes split or merge outside the camera views, the proposed method establishes the weighted correspondence among the exits and entries of the foreground regions based on their correspondence confidence. Experimental results have shown that the adaptively determined time window was effective in terms of both the accuracy and the delay in people counting and the weighted correspondence was effective in terms of the accuracy especially when the people traffic gets congested and groups of people split/merge outside the camera views.

People Counting Across Non-overlapping Camera Views by Flow Estimation Among Foreground Regions

Counting the number of people traveling across nonoverlapping camera views generally requires every person who has exited a camera view to be reidentified when he/she reenters another camera view. A typical solution is to detect an individual person exiting or entering each camera view and establish their correspondence based on their visual appearances and the knowledge of the camera topology, transition time between cameras, etc. One of the main challenges is that the appearances of different people can be similar, while the appearance of the same person can vary in different camera views. On the other hand, a recent approach for counting people within a single camera view is “crowd-centric”, which is to extract foreground regions and estimate the crowd density of the regions. Considering that people often walk together with their acquaintances but not with strangers, the reidentification solution can be applied to the foreground regions to reidentify the groups of people. In this case, another problem arises, that is, people sometimes meet or part outside the field of views of the cameras. Thus, a foreground region can have correspondence with multiple foreground regions. Our proposed method handles both of these problems by estimating the flows from the foreground regions exiting the camera views to those entering other camera views based on the confidence levels of their correspondence and the constraints defined by the relationships among their areas. The estimated flows are then summed up to count the people traveling across each pair of cameras.

Optimal Design of Product Family Throughout Commonalization, Customization and Lineup Arrangement

Product family design is a framework for effectively and efficiently meeting with spread customers’ needs by sharing components or modules across a series of products. This paper systematizes product family design toward its extension to throughout consideration of commonalization, customization and lineup arrangement under the optimal design paradigm. That is, commonalization is viewed as the operation that restricts the feasible region by fixing a set of design variables related to commonalized components or modules against later customization and final lineup offered to customers. Customization is viewed as the operation that arranges lineup by adjusting another set of design variables related to reserved freedom for customers’ needs. Their mutual and bi-directional relationships must be a matter of optimal design. This paper discusses the mathematical fundamentals of optimal product family design throughout commonalization, customization and lineup arrangement under active set strategy, and demonstrates a case study with a design problem of centrifugal compressors for showing the meaning of throughout optimal design.Copyright