Subsystem Design Research Articles

Supporting Early Stage Set-Based Concurrent Engineering with Value Driven Design

AbstractSet-Based Concurrent Engineering is commonly adopted to drive the development of complex products and systems. However, its application requires design information about a future product that is often not mature enough in the early design stages, and that it is not encompassing a service and lifecycle- oriented perspective. There is a need for manufacturers to understand, since the early design stages, how customer value is created along the lifecycle of a product from a hardware and service perspective, and how to use such information to screen radically new technologies, trade-off promising design configurations and commit to a design concept. The paper presents an approach for the multidisciplinary value assessment of design concepts in sub-systems design, encompassing the high-level concept screening and the trade-off of different design concepts, and enabling the integration of value models results into a Set-based Concurrent Engineering process. The approach is described through its application in the case study of the development of a subsystem component for a commercial aircraft engine.

Sequential Updating of Quantitative Requirements for Increased Flexibility in Robust Systems Design

AbstractIn early development stages of complex systems, interacting subsystems (including components) are often designed simultaneously by distributed teams with limited information exchange. Distributed development becomes possible by assigning teams independent design goals expressed as quantitative requirements equipped with tolerances to provide flexibility for design: so-called solution-spaces are high-dimensional sets of permissible subsystem properties on which requirements on the system performance are satisfied. Edges of box-shaped solution spaces are permissible intervals serving as decoupled (mutually independent) requirements for subsystem design variables. Unfortunately, decoupling often leads to prohibitively small intervals. In so-called solution-compensation spaces, permissible intervals for early-decision variables are increased by a compensation mechanism using late-decision variables. This paper presents a multi-step development process where groups of design variables successively change role from early-decision to late-decision type in order to maximize flexibility. Applying this to a vehicle chassis design problem demonstrates the effectiveness of the approach.

Design, Analysis and Performance Evaluation of Electrical Power Subsystem based on Triple-Junctions Solar PV Cells and SEPIC for a Conceptual 1u Cubesat Mission

This study aims to popularize low voltage power supply design especially for space satellite Cubesat mission and other portable consumer electronic devices. In this context, a preliminary design of an electrical power subsystem (EPS) is carried out for a conceptual 1u Cubesat mission in this paper. Mathematical modeling of the basic elements of the EPS is presented. Photovoltaic (PV) power generation system that is selected is made up of triple-junction solar cells, and the battery charging system based on lithium technology as well as the power conditioning converters are selected based on single ended primary inductance converter topology popularly abbreviated as SEPIC. Triple-junction solar PV cell results are verified by comparing with the datasheet values. A maximum power point tracking algorithm which is known as perturb and observe is implemented and proportional-integral controller is used for the SEPIC. All of these are well analyzed, mathematically modeled and simulated. Feasibility of the designed EPS is verified by comparing with similar devices from different manufacturers.

BARRIERS TO RADICAL INNOVATIONS AS STABLE DESIGNS: INSIGHTS FROM AN IT CASE STUDY

Radical innovations start as product innovations in sub-systems of the socio-technical system. External triggers cause product innovations which in turn influence transitions of a socio-technical system. Socio-technical systems require configurations and/or customisations to multiple sub-systems not necessarily to ICT alone. Expansions to product innovations in the sub-systems are required to provide meaningful designs. Actors combine meaningful designs of various sub-systems and devise solutions and its adoption. Product innovations cumulate as stable designs when solutions meet end-users wants and needs, and require changes to policies, procedures, and methods used during devising and adoption of the solution. In other words, we require process innovations. The author using a single case study examines the above phenomena. The methods and theories towards process innovations assist in expanding the existing socio-technical transition theories, especially Multi-Level Perspective (MLP), thereby assisting actors in analysing, learning, adjusting, and internalise innovations while they navigate, struggle, and negotiate alternatives.

Automated storage and retrieval system for Industry 4.0 concept

This paper presents the results of research that focused on the implementation of the intelligent design and development of subsystems meeting the requirements of the Industry 4.0 concept. The main emphasis is on a mathematical model of the digital interaction between two key components of the flexible automated production, which consists of warehouse adaptable to changing production and service equipped by robot with sensors for receiving the whole set of information. Mathematical formalisms were developed and computer calculations were carried out in order to meet these problems.

Design and Development of 4-MJ Capacitor Bank-Based Pulsed Power System for Electromagnetic Launcher

A capacitor-based pulsed power system of 4 MJ was designed and developed to propel projectiles of mass above 100 g to hypervelocites. The system used the modular approach, by integrating ten 400-kJ capacitor bank modules. A number of simulation studies were carried out viz., performance analysis of the system using Microcap simulation package, design of various pulsed power subsystems using ANSYS Maxwell simulation tool, and finite element transient analysis for current diffusion through the in-house developed software. Power transfer lines, coaxial cables, and pulse-shaping inductor were designed and fabricated. Various electromagnetic (EM) launchers were designed, developed, and fabricated. Modules are arranged on various racks and are integrated with the EM launcher. Launchers are initially test fired with four modules and then with ten modules. The data acquisition system was developed to measure module currents, in-bore position, velocity, and acceleration of armature. The pulsed power system was experimented up to 1.1-MA current pulse and was successfully test fired to accelerated 120-g mass projectile at a muzzle velocity of 2024 m/s.

Multi‐objective optimization of solar‐aided coal‐fired power generation system under off‐design work conditions

AbstractSolar‐aided coal‐fired power generation (SAPG) has been attracting more and more attentions in recent years. However, the multi‐objective optimization of SAPG system considering off‐design work conditions has not been fully studied. In this paper, a general system integration optimization method (GIOM) has been developed for integration schemes optimization, and Nondominated Sorting Genetic Algorithm‐II (NSGA‐II) algorithm is used for multi‐objective optimization of SAPG system. As a case study, a SAPG system that refers to a real 600 MWe supercritical coal‐fired power plant is optimized based on a typical day. By simultaneous optimization of both initial investment (P) and solar net electric generation (Esolar), the solar subsystem design schemes are optimized as Pareto optimal set. At last, to maximum Esolar/P, the final design scheme is selected from the Pareto optimal set, whose Esolar and P are 237.6 MWh and 113.5 M$, respectively. The results show that, the final design scheme is a heliostat field with instantaneous optical efficiency of 63.24% at the design point, the receiver power rating is 133 MWt, the tower height is 136.6 m, and distances of successive rows of the three zones are 13.6, 17.7, and 24.5 m, respectively. A larger or smaller size of solar subsystem is considered to be uneconomical.

A Data-Driven Adaptive Method for Attitude Control of Fixed-Wing Unmanned Aerial Vehicles

In this paper, a real-time online data-driven adaptive method is developed to deal with uncertainties such as high nonlinearity, strong coupling, parameter perturbation and external disturbances in attitude control of fixed-wing unmanned aerial vehicles (UAVs). Firstly, a model-free adaptive control (MFAC) method requiring only input/output (I/O) data and no model information is adopted for control scheme design of angular velocity subsystem which contains all model information and up-mentioned uncertainties. Secondly, the internal model control (IMC) method featured with less tuning parameters and convenient tuning process is adopted for control scheme design of the certain Euler angle subsystem. Simulation results show that, the method developed is obviously superior to the cascade PID (CPID) method and the nonlinear dynamic inversion (NDI) method.

Smartfloat: A Multimodal Underwater Vehicle Combining Float and Glider Capabilities

This paper proposes a novel hybrid underwater vehicle, the Smartfloat, which integrates the concept of buoyancy-driven underwater gliders and conventional profiling floats. The vehicle is presented to address the challenges in ocean monitoring, such as the multidisciplinary observations of long-range transport of the mesoscale features with high spatial-temporal resolution. The vehicle combines the mechanisms of Argo profiling float and the underwater glider, with the application of a special designed attitude control system and the ingenious general arrangement. The vehicle can switch the operating mode between drifting mode and gliding mode. Such a multimodal vehicle would merge the benefits of making measurements in a very energy-efficient way when drifting with the currents in Argo mode, and operating as an underwater glider in glider mode when it is needed to cross the ocean eddies, ocean fronts, filaments, or some stirring regions. In this paper, a proof-of-concept platform including its concept of operations, the main components and subsystems design, and the correlative mathematical analysis is introduced in detail. Experiments in field trials are presented to characterize and illustrate each mode of operation and repeated mode transitions. The results demonstrate the feasibility and the good performance of the proposed vehicle.

The development of a data collection and analysis system based on social network users’ data

The general concept and implementation of a practice-oriented social network data storage and analysis system are discussed in this paper. The need for such a concept comes from the fact that at the moment little attention is paid to the internal structure of such systems. The proposed system organizes the process of collecting data, filling the database from third-party sources and analyzing the collected data. The main problem of gathering fragmented data from different sources is also addressed. Due to the variety of possible information formats, approaches for designing efficient data warehouse for further social network user’s data analysis are discussed in this paper. Considered approach for design and implementation of the data collection subsystem can be used for storing user’s data with the current trends in the development of social networks. The problem of data confidentiality in such systems is also discussed. An example is provided for the implementation of the main parts of the system.

Full State Tracking and Formation Control for Under-Actuated VTOL UAVs

In this paper, a coupled-attitude based trajectory tracking scheme is proposed to track both the position and attitude of under-actuated unmanned aerial vehicles, and its application on formation control is further demonstrated. An intermediate attitude which is composed of the desired attitude and position information is designed in a two-stage framework, wherein the first stage is the controller design of a translational subsystem and the second stage is that of an attitude subsystem. By virtue of the intermediate attitude, trajectory tracking which includes both attitude and position is realized. The proposed intermediate attitude can be viewed as a bridge connecting the position and attitude motion, and it is a new approach for both single and multiple under-actuated rigid bodies’ control. Based on the approach of coupled-attitude-based trajectory tracking, both the set point stabilization and formation tracking tasks for under-actuated vertical takeoff and landing vehicles over a directed acyclic graph can be achieved. The performances of the proposed control laws are illustrated through numerical simulations.

Novel, shape optimised, TEG subsystem design

This research report presents a new, innovative design and manufacturing solution to recover thermal waste heat energy, from the combustion process of the engine, without affecting the process. Our research focuses on the exhaust port of the engine cylinder, were the waste heat energy and engine coolant are available to operate the thermoelectric generator (TEG) units. A new, one-piece TEG unit, is designed and computational fluid dynamics (CFD) analyzed, to evaluate and validate effective thermal waste heat transfer into the unit subsystem, at the temperatures ranging over 800°C. Additional simulations, on the internal combustion engine (ICE) cylinder head provided data of the flow temperature distribution when directly coming from the heat source. Using TEG units’ test data, from our experiments, and data generated from our Matlab-Simulink model, we were able to validate and predict performances of the new TEG subsystem design. Our solution ensures the best surfaces matching, between the oval shaped TEG subsystem and the engine hot surface. Following that, it offers optimal energy recovery.

Design of Modular Power Management and Attitude Control Subsystems for a Microsatellite

The Electric Power System (EPS) and attitude control system (ACS) are the essential components of any satellite. EPS and ACS efficiency and compactness are substantial for the proper operation and performance of the satellite’s entire mission life. So, realizing the significance of EPS and ACS subsystems for any satellite, they have been assimilated and developed in modular forms focusing on efficiency and compactness. The EPS is comprised of three modules called the solar panel module (SPM), power conditioning module (PCM), and power distribution module (PDM) while the ACS has an embedded magnetorquer coil. For compactness and miniaturization purposes, the magnetorquer coil is embedded inside the SPM. The components used are commercial off-the-shelf (COTS) components emphasizing on their power efficiency, small dimensions, and weight. Latch-up protection systems have been designed and analyzed for CMOS-based COTS components, in order to make them suitable for space radioactive environment. The main design features are modularity, redundancy, power efficiency, and to avoid single component failure. The modular development of the EPS and ACS helps to reuse them for future missions, and as a result, the overall budget, development, and testing time and cost are reduced. A specific satellite mission can be achieved by reassembling the required subsystems.

Preliminary design of communication and power subsystem for micro-satellite with maritime surveillance mission

Vast maritime territory in Indonesia needs satellite technology to prevent illegal activities such as illegal fishing, fuel dumping, illegal transhipment, and trafficking/smuggling. Therefore, this research aims to design a satellite with mission for detecting illegal activities on Indonesian territorial water and ZEE. The satellite will have the capability to receive AIS signal from ships operating in Indonesian territory, and image signature for optical or radar sensor capture it by SAR. The concept of operation is that the satellite will receive/capture the ships information and send the real-time data while passing Indonesian region. Thereafter, the data received is then processed in ground segment to determine suspected ships. In this paper, the discussion focuses on the design of the satellite communication and power subsystem. In this work, LAPAN’s micro-satellite design is selected as the base to determine and size components of the subsystem. Satellite communication link budget was calculated with three alternatives of antenna to determine which one has the best link performance. Afterwards, the power subsystem which consists of solar cell, as the main power generator, and battery units was designed. The result of the work is a preliminary satellite design of the subsystems, that satisfy the satellite mission requirements.

THEOREM ABOUT KEY CAPACITY OF A COMMUNICATION NETWORK

Introduction : An important aspect of cryptographic telecommunication systems is the encryption key control problem. The most complicated stages in its solution are the safe generation of the keys, their distribution, and their delivery to legitimate subscribers via protected communication channels, which is fairly expensive, sometimes slow and not always possible. As an alternative, the keys can be generated by transferring information via telecommunication channels, being possibly exposed to a violator. The known estimations of information efficiency look like a solution of sophisticated information theory problems for certain ways of open key coordination between two legitimate subscribers. Efficiency estimations for the conditions of network key generation are not known. Purpose : A s trictly conclus ive search for potential estimates of information efficiency of open network key gener ation. Results : Within the formulated statement of the problem, we have proposed a violator model and a network channel connectivity model which is a combination of a broadcast channel connecting three legitimate subscribers and an intercept channel at the output of which the violator controls the transferred information. The information exchange is based on the proposed models of a random coder and deterministic decoder with a specially developed asymptotic method of key generation. In order to assess the process, we introduce a system of quality indicators and requirements which differs from the known ones by its definition of “information” speed of network key generation. We also introduce a term of key network capacity which determines the asymptotic information efficiency of the key generation. We have formulated and rigorously proved a theorem about key capacity. The boundary values have been substantiated . Practical relevance : The obtained results develop the known scientific achievements in the field of open key coordination theory and can be used by specialists in the design and development of key control subsystems in modern cryptographic information security systems which provide closed network information exchange.

OMOTENASHI trajectory analysis and design: Landing phase

OMOTENASHI is a JAXA 6U cubesat that aims to perform a semi-hard landing on the Moon's surface after being deployed into a lunar fly-by orbit by the American Space Launch System, Exploration Mission-1. OMOTENASHI is a challenging mission – performing a semi-hard landing with a cubesat. One of the main challenges comes from the trajectory, which is characterized by a single deceleration maneuver instead of multiple ones for orbit insertion, descent, hovering and landing. After the deceleration maneuver, there is no time to correct for navigation and execution errors so the robustness of the trajectory is key. This paper presents the analysis and design of the OMOTENASHI landing phase. It studies the performance of the subsystems involved in the landing and proposes a deceleration maneuver to set to zero the vertical velocity at burn-out with a specified height over the Moon's surface, followed by a free-fall. In order to assess the robustness of the trajectory, it considers uncertainties in the state vector and deceleration maneuver execution. The flight path angle at lunar arrival has a great impact on the landing success rate, which imposes a very strong constraint on the design of the transfer phase trajectory. Under the current subsystems design, the most critical factors in the landing success rate are the maneuver orientation and thrust duration. Results suggest accuracy requirements for the landing devices, solid rocket motor and attitude accuracy, as well as for the transfer phase trajectory design. Finally, the navigation and maneuver execution errors may cause OMOTENASHI to prematurely impact against the surface during the solid rocket motor burn. This calls for a trade-off between the targeted final height and the maximum landing velocity.

Statistical physics of design

A key challenge in complex design problems that permeate science and engineering is the need to balance design objectives for specific design elements or subsystems with global system objectives. Global objectives give rise to competing design pressures, whose effects can be difficult to trace in subsystem design. Here, using examples from arrangement problems, we show that the systems-level application of statistical physics principles, which we term ‘systems physics’, provides a detailed characterization of subsystem design in terms of the concepts of stress and strain from materials physics. We analyze instances of routing problems in naval architectures, and show that systems physics provides a direct means of classifying architecture types, and quantifying trade-offs between subsystem- and overall performance. Our approach generalizes straightforwardly to design problems in a wide range of other disciplines that require concrete understanding of how the pressure to meet overall design objectives drives the outcomes for component subsystems.

Development of torque clutch drilling tool and evaluation of drag reduction performance

Horizontal well is one of the important methods of unconventional oil and gas resource development. As increasing length of horizontal section, there is a serious problem that axial force cannot transfer to bit. The drilling field needs a low-friction and low-cost drag reduction tool. This article summarized existing technologies of drag reduction in the horizontal and inclined well and proposes an integrated design of torque clutch. Detailed design of tool sub-systems is introduced. The tool includes three sub-systems: clutch, hydraulic system, and monitoring system. The clutch is consisted of multiple clutch units mounted in a parallel arrangement. Power of hydraulic control system adopts difference in pressure between inside and outside of drill pipes. It can efficiently reduce power consumption. The design function and minimum working pressure are validated and obtained by indoor test. According to theoretical calculation, reasonable distance from tool to bit can be obtained for an actual drilled well. During directional drilling mode, the tool can reduce more than 30% axial drag of drill string according to theoretical calculation. The tool can effectively improve the capacity of transfer weight to bit and overcome the excessive drag in horizontal drilling. No similar tools are reported in the current field.

Analysis and design of a stacked power subsystem on a picosatellite

In 1999, the satellite classification was developed and given to a standard-sized, limited-weight picosatellite [1] in a multidisciplinary didactic format, signed between Stanford University and Polytechnic University of California. The CubeSat standard provides a development platform accessible to both universities and small businesses to develop research and technology at a reduced cost [2]. Furthermore, a CubeSat project uses commercial-off-the-shelf components to further reduce cost.

Unveiling Product-Organization Interactions in Projects Delivering Innovative Solutions

Innovation in complex projects imply that neither the product nor the organization subsystem designs can be predefined in detail at the start of the project but they both are developed and change o...