Optimal Design Plan Research Articles

Optimal designs and reliability sampling plans for one-shot devices with cost considerations

In this paper, we investigate some statistical inference, optimal design, and reliability sampling plan problems related to multiple constant-stress accelerated life test with one-shot device testing. At each stress-level combination, a generalized exponential lifetime distribution is considered. The scale parameter of the proposed distribution is assumed to be a log-linear function of stresses. To conduct a one-shot device accelerated life test more efficiently, one has to address the problem of determining optimal setting that produces the best estimation results. In practice, the experimental budget is always limited. The size of budget usually influences the decision of experimental setting and hence, influences the precision of estimation. Therefore, this paper is to determine the optimal experimental setting under D-optimality criterion with cost constraint. In addition, reliability sampling plan is an important statistical tool in the area of quality control. This paper is also to explore the optimal reliability sampling plan which minimizes the total experimental cost of a one-shot device accelerated life test with specified producer’s risk and consumer’s risk.

Integrating first-mile pickup and last-mile delivery on shared vehicle routes for efficient urban e-commerce distribution

In this paper, we analyze the route efficiency trade-offs that emerge from combining first-mile pickup and last-mile delivery operations in an urban distribution system. We build on the extant literature on continuum approximation of optimal route distances and propose adjustment factors that account for the effects of integrated pickup and delivery operations. By means of comprehensive numerical experiments and regression analysis, we further propose a set of closed-form adjustment factors that improve existing continuum approximation-based route length estimations. These adjustment factors incorporate some non-trivial route efficiency trade-offs emerging from first-mile and last-mile integration that cannot easily be captured through continuum approximation. The proposed extensions are particularly relevant for the optimal strategic design and operational planning of large-scale, high-density last-mile distribution systems that are gaining in importance in light of e-commerce and omni-channel retailing. Our analyses suggest that the efficiency gains emerging from integrating first-mile pickup and last-mile delivery operations can be as high as 30%. However, the effective efficiency gains are sensitive to vehicle capacity constraints and other factors complicating the optimal stop sequence in integrated routes. We apply our proposed method to a real-world case study informed by operational data from one of India’s largest e-commerce platforms for the city of Bengaluru. We find that by properly integrating its first-mile and last-mile operations, the company could reduce its urban traffic and emissions impact by up to 16%, while increasing the asset utilization and reducing the cost of operations of its vehicle fleet.

An optimal concurrent product design and service planning approach through simulation-based evaluation considering the whole product life-cycle span

A new approach is introduced in this research to identify the optimal product design and its service plan concurrently through simulation-based evaluation considering the whole product life-cycle span. In this approach, the generic product design is modeled by an AND-OR tree with parameter variables, and the specific design candidates and their design parameter values are created from the AND-OR tree. In the same way, the generic service plan is modeled by an AND-OR tree with parameter variables, and the specific service plan candidates and their service parameter values are created from the AND-OR tree. In the whole product life-cycle span, the product components, parameter values and functional performances are changed due to service activities such as maintenances and repairs. Simulation approach is employed to evaluate serviceability of the product in its whole life-cycle span considering different product designs, design parameters, service plans, and service parameters. A multi-level and multi-objective optimization method is developed to identify the optimal product design, design parameter values, service plan and service parameter values. A case study is implemented to show the newly introduced optimal concurrent product design and service planning approach.

A risk-averse stochastic program for integrated system design and preventive maintenance planning

The failure of high-consequence systems, such as highspeed railways, can result in a series of severe damages. Due to the volatility of real circumstances, stochastic optimization methods are needed to aid decisions on reliability design and maintenance for the high-consequence systems. Traditionally, risk-neutral approaches are used by considering the expectation of random variables as a preference criterion. The risk-neutral approaches may achieve the solutions that are good in the long run but do not control poor results under certain realizations of random variables. From a perspective of risk analysis, such solutions are not acceptable for high-consequence systems. To address this issue, this paper uses the conditional value at risk (CVaR) to more properly account for some of the worst realizations of random future usage scenarios, and then proposes a risk-averse two-stage stochastic programming model to simultaneously determine the numbers of components in each subsystem and preventive maintenance time intervals for the high-consequence systems that are exposed to uncertain future usage stresses. The proposed stochastic programming model can be converted to a nonconvex mixed-integer nonlinear programming (MINLP) model. To solve the model, we derive the analytical properties of the recourse function and the closed form of CVaR and then design a decomposition algorithm. Numerical examples demonstrate the proposed risk-averse stochastic approach and the effectiveness of incorporating the CVaR in modeling. The results show the research problem significantly benefits from the proposed approach. Furthermore, the robustness of the optimal system design and maintenance plan under different profiles of future usage scenarios is addressed.

Quasidistributed optical fiber sensing system to monitor the displacement of joints on the face slab of concrete-faced rockfill dams

We propose a quasidistributed optical fiber-sensing system based on optical time-domain reflectometry (OTDR). The quasidistributed optical fiber-sensing system can be used to monitor the joint opening displacement or crack opening displacement of the face slab of concrete-faced rockfill dams (CFRDs). The crack sensors, which are based on the sensing principle of linear macrobending loss of optical fiber, are connected in series in each optical fiber link. In addition, multiple links can be connected with a single OTDR to construct an integrated monitoring system. Hence, the quasidistributed system overcomes some drawbacks of the distributed monitoring system, such as limited measurement range, fragility of fibers attached to the structural surface, and the nonlinear relationship between displacement and macrobending loss of optical fiber. To develop an optimal design plan for the monitoring system, some experiments are conducted to verify the independence of crack sensors and the minimum length of the connecting fiber between sensors. The analysis of the experiment results positively supports the application of optical loss in real structural monitoring.

Optimal platform design and process plan for managing variety using hybrid manufacturing

A novel generic process planning concept is introduced to manage the variety of product families produced by hybrid manufacturing. An optimal product family platform containing the core features of all variants is first developed. A combination of additive and subtractive processes of a product variant differentiating features determines its optimal process plan and minimizes manufacturing cost. The developed mixed integer linear programming model and a case study used for demonstration are presented. This novel planning approach is adaptable to changes in products design and demands. It will impact the use of additive processes to manufacture product families and its cost.

Techno‐economic assessment of employing hybrid power system for residential, public, and commercial buildings in different climatic conditions of Iran

As the world population grows rapidly, and the limited amount of fossil fuels begins to diminish along with their impact on the environment, countries have been taking action to promote a greater use of renewable energy resources. In this article, the feasibility of providing electricity from a hybrid power system (HPS) comprising diesel/wind/photovoltaic (PV), and battery considering residential, public, and commercial buildings, consuming the largest portion of energy in Iran is investigated. Tehran, Kish Island, and Binalood are the chosen cities in Iran with distinctive geographic and climatic conditions. In order to determine the optimal design and operational planning of the HPS, the hourly electricity demand data is required to be over 8760 hs during a 1‐yr study. The required hourly data was calculated by employing Carrier (HAP4.5) software. The economic analysis is performed based on net present cost (NPC), cost of energy (COE), diesel consumption, and renewable fraction for all cases by applying HOMER software. Furthermore, sensitivity analyses are carried out to specify the impact of fuel cost on the system by considering two different diesel fuel systems. The results of the economic analysis indicate that Kish Island with warm and temperate climatic conditions would be the optimum zone to install HPS for supplying the energy demand of projected buildings. © 2018 American Institute of Chemical Engineers Environ Prog, 38: 614–623, 2019

Dynamic Supply Chain Design and Operations Plan for Connected Smart Factories with Additive Manufacturing

Interest in smart factories and smart supply chains has been increasing, and researchers have emphasized the importance and the effects of advanced technologies such as 3D printers, the Internet of Things, and cloud services. This paper considers an innovation in dynamic supply-chain design and operations: connected smart factories that share interchangeable processes through a cloud-based system for personalized production. In the system, customers are able to upload a product design file, an optimal supply chain design and operations plan are then determined based on the available resources in the network of smart factories. The concept of smart supply chains is discussed and six types of flexibilities are identified, namely: design flexibility, product flexibility, process flexibility, supply chain flexibility, collaboration flexibility, and strategic flexibility. Focusing on supply chain flexibility, a general planning framework and various optimization models for dynamic supply chain design and operations plan are proposed. Further, numerical experiments are conducted to analyze fixed, production, and transportation costs for various scenarios. The results demonstrate the extent of the dynamic supply chain design and operations problem, and the large variation in transportation cost.

Application of the Fast Marching Method for Path Planning of Long-haul Optical Fiber Cables With Shielding

This paper provides a method for optimal shielding design and path planning of a long-haul optical fiber cable between two locations on the Earth’s surface. The method allows minimization of the cable laying cost including material and labor and the risks of future cable break associated with laying the cable through various areas, including earthquake-prone or other risky areas. Both costs per unit length and risk of cable damage may be different at different locations. Expensive shielding may be important in certain high-risk areas and unnecessary in lower risk areas. We use ground motion intensity to estimate future cable repair rate (our measure of earthquake-related cable damage risk), and a triangulated manifold to represent the surface of the Earth. With laying cost and expected total number of repairs of the cable as the two objectives, we formulate the problem as a multiobjective variational optimization problem. This formulation incorporating multiple design levels for cable shielding is converted into a single objective variational optimization problem by assigning different weights to each objective. The solution path of the later problem is obtained by using the Fast Marching Method (FMM) with an additional minimization step. A new proof of the optimality of FMM for the problem is provided. Numerical results demonstrate that the FMM-based method outperforms existing raster-based algorithms. With billions of US dollars spent yearly on new cables, the potential savings are substantial. Furthermore, the computational complexity of the FMM-based method is $O(N \log (N))$ , making it applicable to cables of realistic length.

Interior Ballistic Modeling and Charge Structure Optimization of Cased Telescoped Ammunition

In order to improve the muzzle velocity of the cased telescoped ammunition (CTA) with a certain caliber, a kind of charge structure with the shear form when engraving the grooves of the CTA was designed, a theoretical interior ballistic model was established and the optimization design plan was proposed. Results show that the interior ballistic model can generally describe the interior ballistic characteristics of the CTA, the calculated results agree well with the experimental ones. On the basis, by optimizing the charge structure parameters of the CTA using the multi-objective particle swarm optimization algorithm, the muzzle velocity of the projectile is improved by 2.58% with the maximum chamber pressure unchanged. The study can provide reference for the interior ballistic modeling and the charge structure of the CTA.

Application of 3D Laser Scanning Technology in Complex Rock Foundation Design

Taking the complex landform of Tanxi Mountain Landscape Bridge as an example, the application of 3D laser scanning technology in the mapping of complex rock foundations is studied in this paper. A set of 3D laser scanning technologies are formed and several key engineering problems are solved. The first is 3D laser scanning technology of complex landforms. 3D laser scanning technology is used to obtain a complete 3D point cloud data model of the complex landform. The detailed and accurate results of the surveying and mapping decrease the measuring time and supplementary measuring times. The second is 3D collaborative modeling of the complex landform. A 3D model of the complex landform is established based on the 3D point cloud data model. The super-structural foundation model is introduced for 3D collaborative design. The optimal design plan is selected and the construction progress is accelerated. And the last is finite-element analysis technology of the complex landform foundation. A 3D model of the complex landform is introduced into ANSYS for building a finite element model to calculate anti-slide stability of the rock, and provides a basis for the landform foundation design and construction.

Researches in Optimization Selection of Design Scheme of Underground Natural Gas Storage Based on TOPSIS Method

As the increasing importance of natural gas in the energy consumption of our country, the natural gas consumption has been rising year by year. In order to avoid gas shortage, the most effective way is to storage the natural gas, while the best method is to build underground natural gas storage. There are different choices for the storage design regarding to the specifications. Therefore, it is of great importance and critical to optimize the design schemes of underground storage. In this study, we extract the key evaluation indices on the basis of previous researches. An innovative combination of analytic hierarchy process and TOPSIS method have been used to determine the optimal design plan of natural gas storage reasonably.

Dynamic simulation analysis of effects of project of ditching for drain on Oncomelania hupensis snail control and flood prevention security in Dongting Lake region

To evaluate the effects of the project of ditching for drain on Oncomelania hupensis snail control and flood prevention security and explore the optimal engineering design plan in Dongting Lake region. A retrospective study was performed on the previous studies about the project of ditching for drain. The reference values of project indices were determined. The outside levee of Nanhu New Distinct of Yueyang City in Dongting Lake region was selected as the study area, and the cross section of marshland perpendicular to the center line of the levee was extracted to research. According to the situations of various water levels, a dynamic simulation was performed on the effect and security of the project of ditching for drain through the software FLAC3D. The retrospective study showed that the project would be effective when the relatively subsoil water level decreased by 0.35 m, and the soil water content decreased correspondingly. The dynamic simulation by FLAC3D showed that the minimum safe distances between transverse ditch 1, vertical ditch and levee toe should be 25 m and 13 m respectively. The digging depth of transverse ditch and vertical ditch should be 1.2 m and 1.0 m respectively. If the width of marshland in drought period was less than 500 m, one transverse ditch was efficient. Otherwise, more transverse ditches should be set with the intervals of 300 m. The project of ditching for drain is an effective ecological snail elimination method. Optimizing the digging depth of ditches and distances between transverse ditches, vertical ditch and levee toe will ensure the effects and security of the project.

Circuit Simulation for Bridge Ignition Feature of Semiconductor

The emergence of ignition device of semiconductor bridge provides a way to resolve the conflict between low energy and high promptness, reliability and safety of initiating explosive device. But with the rapid development of arms and ammunition, the higher demand of miniaturization for structure and volume in design of initiating explosive device is put forward based on high safety, reliability and promptness and low ignition energy. The heat dissipation effect of all structural parts is assessed, the measures to optimize the structure are put forward, the numerical simulation is adopted for simulation and the accuracy of optimization design plan is finally physically verified in the Thesis based on thermal analysis of ignition device of semiconductor bridge in maximum no-fire test. The finite-element numerical simulation analysis provides theoretical basis and comparison and assessment of various plans in optimization design for ignition device of semiconductor bridge, and greatly shortens the time and reduces the design errors in optimization design for ignition device of semiconductor bridge; meanwhile, it assists in product development and design as the platform for design, analysis and verification.

Thermal Environment Dynamic Simulation of Double Skin Façade with Middle Shading Device in Summer

Double-skin facade (DSF) can be thermal insulation either in summer or winter. While building shading devices can reduce the solar radiation heat gain through windows effectively, save building energy consumption and improve indoor thermal environment quality in summer. Based on the dynamic simulation of the indoor environment, this paper puts the blinds inside the intermediate cavity, simulates the effect of different locations and inclinations, analysis their influence on ventilation effect, intermediate cavity temperature and indoor temperature. And finally, a relatively optimal design and utility plan is summarized to provide some references for middle shading device design and evaluation of this field.

Optimization Analysis on Upper Filter System of Mechanical Water Treatment Equipment Based on Strength

Domestic water treatment is very important field. Now, mechanical water treatment technology is getting wide use in production. In the process of life water treatment, filter process is a very important step. In this paper, the strength and deformation of upper filter system which includes upper filter frames and upper filter plates were analyzed with ANSYS and useful results are got. Through the analysis on strength, the paper found the shortcomings of production and design. After analyzing and comparing the stresses and deformations of three different design schemes, the paper provided the optimized design plan of upper filter system at last.

Optimal pavement design and rehabilitation planning using a mechanistic-empirical approach

This paper presents the development of a pavement design and rehabilitation optimization decision-making framework based on Mechanistic-Empirical (ME) roughness transfer models. The AASHTOWare Pavement ME Design (the software of Pavement ME Design) is used to estimate pavement deterioration based on the combined effects of permanent deformation, fatigue, and thermal cracking. The optimization problem is first formulated into a mixed-integer nonlinear programming model to address the predominant trade-off between agency and user costs. To deal with the complexity associated with the pavement roughness transfer functions in the software and to use the roughness values as input to the optimization framework, a dynamic programming subroutine is developed for determining the optimal rehabilitation timing and asphalt concrete design thickness. An application of the proposed model is demonstrated in a case study. Managerial insights from a series of sensitivity analyses on different unit user cost values and model comparisons are presented.

Hierarchical Kinematic Modelling and Optimal Design of a Novel Hexapod Robot with Integrated Limb Mechanism

This paper presents a novel hexapod robot, hereafter named PH-Robot, with three degrees of freedom (3-DOF) parallel leg mechanisms based on the concept of an integrated limb mechanism (ILM) for the integration of legged locomotion and arm manipulation. The kinematic model plays an important role in the parametric optimal design and motion planning of robots. However, models of parallel mechanisms are often difficult to obtain because of the implicit relationship between the motions of actuated joints and the motion of a moving platform. In order to derive the kinematic equations of the proposed hexapod robot, an extended hierarchical kinematic modelling method is proposed. According to the kinematic model, the geometrical parameters of the leg are optimized utilizing a comprehensive objective function that considers both dexterity and payload. PH-Robot has distinct advantages in accuracy and load ability over a robot with serial leg mechanisms through the former's comparison of performance indices. The reachable workspace of the leg verifies its ability to walk and manipulate. The results of the trajectory tracking experiment demonstrate the correctness of the kinematic model of the hexapod robot.

Integrated decision making for the optimal bioethanol supply chain

Bioethanol production poses different challenges that require an integrated approach. Usually previous works have focused on specific perspectives of the global problem. On the contrary, bioethanol, in particular, and biofuels, in general, requires an integrated decision making framework that takes into account the needs and concerns of the different members involved in its supply chain.In this work, a Mixed Integer Linear Programming (MILP) model for the optimal allocation, design and production planning of integrated ethanol/yeast plants is considered. The proposed formulation addresses the relations between different aspects of the bioethanol supply chain and provides an efficient tool to assess the global operation of the supply chain taking into account different points of view. The model proposed in this work simultaneously determines the structure of a three-echelon supply chain (raw material sites, production facilities and customer zones), the design of each installed plant and operational considerations through production campaigns. Yeast production is considered in order to reduce the negative environmental impact caused by bioethanol residues. Several cases are presented in order to assess the approach capabilities and to evaluate the tradeoffs among all the decisions.

Optimal grid design and logistic planning for wind and biomass based renewable electricity supply chains under uncertainties

In this work, the grid design and optimal allocation of wind and biomass resources for renewable electricity supply chains under uncertainties is studied. Due to wind intermittency, generation of wind electricity is not uniform and cannot be counted on to be readily available to meet the demand. Biomass represents a type of stored energy and is the only renewable resource that can be used for producing biofuels and generating electricity whenever required. However, amount of biomass resources are finite and might not be sufficient to meet the demand for electricity and biofuels. Potential of wind and biomass resources is therefore jointly analyzed for electricity generation. Policies are proposed and evaluated for optimal allocation of finite biomass resources for electricity generation. A stochastic programming model is proposed that optimally balances the electricity demand across the available supply from wind and biomass resources under uncertainties in wind speed and electricity sale price. A case study set in the American Midwest is presented to demonstrate the effectiveness of the proposed model by determining the optimal decisions for generation and transmission of renewable electricity. Sensitivity analysis shows that level of subsidy for renewable electricity production has a major impact on the decisions.