3,713 research outputs found
Intelligent systems in manufacturing: current developments and future prospects
Global competition and rapidly changing customer requirements are demanding increasing changes in manufacturing environments. Enterprises are required to constantly redesign their products and continuously reconfigure their manufacturing systems. Traditional approaches to manufacturing systems do not fully satisfy this new situation. Many authors have proposed that artificial intelligence will bring the flexibility and efficiency needed by manufacturing systems. This paper is a review of artificial intelligence techniques used in manufacturing systems. The paper first defines the components of a simplified intelligent manufacturing systems (IMS), the different Artificial Intelligence (AI) techniques to be considered and then shows how these AI techniques are used for the components of IMS
Complex low volume electronics simulation tool to improve yield and reliability
Assembly of Printed Circuit Boards (PCB) in low volumes
and a high-mix requires a level of manual intervention during
product manufacture, which leads to poor first time yield and
increased production costs. Failures at the component-level
and failures that stem from non-component causes (i.e.
system-level), such as defects in design and manufacturing,
can account for this poor yield. These factors have not been
incorporated in prediction models due to the fact that systemfailure
causes are not driven by well-characterised
deterministic processes. A simulation and analysis support
tool being developed that is based on a suite of interacting
modular components with well defined functionalities and
interfaces is presented in this paper. The CLOVES (Complex
Low Volume Electronics Simulation) tool enables the
characterisation and dynamic simulation of complete design;
manufacturing and business processes (throughout the entire
product life cycle) in terms of their propensity to create
defects that could cause product failure. Details of this system
and how it is being developed to fulfill changing business
needs is presented in this paper. Using historical data and
knowledge of previous printed circuit assemblies (PCA)
design specifications and manufacturing experiences, defect
and yield results can be effectively stored and re-applied for
future problem solving. For example, past PCA design
specifications can be used at design stage to amend designs or
define process options to optimise the product yield and
service reliability
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TAO Conceptual Design Report: A Precision Measurement of the Reactor Antineutrino Spectrum with Sub-percent Energy Resolution
The Taishan Antineutrino Observatory (TAO, also known as JUNO-TAO) is a
satellite experiment of the Jiangmen Underground Neutrino Observatory (JUNO). A
ton-level liquid scintillator detector will be placed at about 30 m from a core
of the Taishan Nuclear Power Plant. The reactor antineutrino spectrum will be
measured with sub-percent energy resolution, to provide a reference spectrum
for future reactor neutrino experiments, and to provide a benchmark measurement
to test nuclear databases. A spherical acrylic vessel containing 2.8 ton
gadolinium-doped liquid scintillator will be viewed by 10 m^2 Silicon
Photomultipliers (SiPMs) of >50% photon detection efficiency with almost full
coverage. The photoelectron yield is about 4500 per MeV, an order higher than
any existing large-scale liquid scintillator detectors. The detector operates
at -50 degree C to lower the dark noise of SiPMs to an acceptable level. The
detector will measure about 2000 reactor antineutrinos per day, and is designed
to be well shielded from cosmogenic backgrounds and ambient radioactivities to
have about 10% background-to-signal ratio. The experiment is expected to start
operation in 2022
Relationship between significant construction safety parameters and on site safety performance of high rise building in Karachi, Sindh Province, Pakistan
Pakistan is a developing country that is currently enjoying relatively substantial growth
in construction activities. Unfortunately, Pakistan’s construction industry suffers from
poor occupational safety and health (OSH) conditions. The framework of the existing
OSH conditions is fragmented and inadequately enforced, making construction sites
more hazardous. Therefore, it is essential to improve OSH conditions in order to
improve safety performance in building construction. Thus, this research aims to find
those significant safety parameters which can significantly enhance the onsite safety
performance of high-rise building construction. Based on an extensive literature
review, sixty (60) safety parameters for enhancing onsite safety performance have
been identified and classified into fourteen (14) groups. In addition, this study also
adopted a quantitative approach, whereby a questionnaire survey was carried out on
two hundred and ten (210) respondents working in high-rise construction projects in
Karachi city of Sindh Province, in order to determine the most significant safety
parameters out of all the identified safety parameters. Initially, data analysis using
SPSS version 26 found that 38 out of 60 safety parameters were the most significant
safety parameters for enhancing onsite safety performance. Furthermore, the results
from principal component factor analysis provided evidence for the eight (08) groups,
consisting of 56 significant safety parameters accounting for 74.686% of the shared
variance. Finally, correlation analysis results revealed that the 08 groups comprising
56 significant safety parameters exhibit small and medium (range from rs=0.247 to
rs=0.334) correlation with onsite safety performance of high-rise building
construction. This empirical analysis has provided a new framework of significant
safety parameters for enhancing onsite safety performance of high-rise building
construction. Therefore, focusing on these safety parameters would improve the
employees’ safety, which will then enhance the overall safety performance on highrise
construction projects. It is hoped that this research can positively benefit the Pakistani construction industry in enhancing the onsite safety performance of highrise
buildings
construction
Multi-Criteria Optimal Planning for Energy Policies in CLP
In the policy making process a number of disparate and diverse issues such as
economic development, environmental aspects, as well as the social acceptance
of the policy, need to be considered. A single person might not have all the
required expertises, and decision support systems featuring optimization
components can help to assess policies. Leveraging on previous work on
Strategic Environmental Assessment, we developed a fully-fledged system that is
able to provide optimal plans with respect to a given objective, to perform
multi-objective optimization and provide sets of Pareto optimal plans, and to
visually compare them. Each plan is environmentally assessed and its footprint
is evaluated. The heart of the system is an application developed in a popular
Constraint Logic Programming system on the Reals sort. It has been equipped
with a web service module that can be queried through standard interfaces, and
an intuitive graphic user interface.Comment: Accepted at ICLP2014 Conference as Technical Communication, due to
appear in Theory and Practice of Logic Programming (TPLP
Design and Realization of Electronic Measurement Systems for Partial Discharge Monitoring on Electrical Equipment
The monitoring of insulations that composing high voltage apparatus and electrical machines is a crucial aspect for a predictive maintenance program. The insulation system of an electrical machine is affected by partial discharges (PDs), phenomena that can lead to the breakdown in a certain time, with a consequent and significant economic loss. Partial discharges are identified as both the symptom and the cause of a deterioration of solid-type electrical insulators. Thus, it is necessary to adopt solutions for monitoring the insulation status. To do this, different techniques and devices can be adopted. During this research activity, two different systems have been developed at the circuit and layout level, which base their operation respectively on the conducted and on the irradiated measurement, in compliance with the provisions of current standards, if foreseen. The first system is based on the use of a classic signal conditioning chain in which gain value can be set through PC control, allowing the conducted measurement of partial discharges in two frequency bands, Low Frequency (LF) and High Frequency (HF). Based on these bands, the application of the system is diversified. In this case, the information obtained from the measurement can be analysed by an expert operator or processed by an intelligent system, obtaining in both cases information on the status of the machine under test. The second makes use of a UHF antenna built on PCB, which takes care of detecting the irradiated signal generated in the presence of discharge activity, which is then appropriately conditioned and processed by analog electronics, to then be acquired through a programmable logic, which interprets it and returns information on the status of the machine, which can also be checked by an expert user. The application of this system is linked to the type of insulation and the type of power supply adopted, which differentiate its characteristics. In both systems, the analysis of the measurement of partial discharges is suitable for the prevention of failures and the planning of suitable maintenance interventions
A Fuzzy Inference System Approach for Evaluating the Feasibility of Product Remanufacture
In the recent past, efforts have been made in enhancing sustainable manufacturing aimed at protecting the environment and saving natural resources. Among the efforts that have been explored include strategies to ensure responsible end-of-life product management so as reduce the impact on the environment and achieve effective use of resources. Towards this end, reduce, reuse and recycle product disposal strategies have found a lot of consideration in manufacturing. Of the product reuse strategies, remanufacturing has been widely applied owing to its unique feature of rendering the remanufactured product as good as new. For remanufacturers, this strategy leads to provision of quality products comparable to new their new counterparts at a reduced cost. Remanufacturing also leads to a sustainable environment through energy and material savings, as well as minimized solid wastes.
Remanufacturing however, poses challenges related to collection of the returns or cores, manufacturing process planning, resource allocation, warranty estimation and redistribution. These challenges are due to product and process complexities, customer requirements, and uncertainties associated with product take back and the remanufactured products’ market-base. Key among these challenges is the remanufacturing process which is complicated, labor intensive with varying process times. In most cases the routing of these processes is stochastic in nature, based on the condition of the returned product. There is also the negative perception among consumers that remanufactured products are less superior to new ones, which calls for the need to allocate preferably longer warranty periods for the remanufactured product to induce confidence in the consumer while at the same time keeping the warranty costs low.
The objectives of this study were informed by challenges faced by a local remanufacturing firm. They include: (1) a detailed study of the current remanufacturing process of the firm’s products; (2) identification of bottlenecks in the process to make recommendations for improvement; (3) develop a decision support system for assessing product remanufacture; (4) assess warranty allocation options for remanufactured product reuse.
The study revealed that there are bottlenecks in the current remanufacturing process and suggested an improvement to enhance efficiency. This bottlenecks include overutilization of some of the process centers such as the diagnostic testing and the after-repair testing centers which lead to the product spending more time in the system than necessary. To improve the system performance the capacities of the bottleneck centers were increased which yielded significant reduction in the time the product spends in the system.
The key contribution of this dissertation is the development of a decision support system based on a bi-level fuzzy linguistic computing approach. This model integrates qualitative and quantitative product attributes in determining the remanufacturability of a product. The fuzzy-based model established remanufacturability metric, herein referred to as an index, is applied to assess the feasibility of remanufacturing two products that were used as a case study. A number of warranty scenarios are considered to ascertain the impact of different warranty periods on the cost of warranty. The results show that the additional warranty cost for product reuse is a function of the period of first use and the residual life of the produc
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A modular hybrid simulation framework for complex manufacturing system design
For complex manufacturing systems, the current hybrid Agent-Based Modelling and Discrete Event Simulation (ABM–DES) frameworks are limited to component and system levels of representation and present a degree of static complexity to study optimal resource planning. To address these limitations, a modular hybrid simulation framework for complex manufacturing system design is presented. A manufacturing system with highly regulated and manual handling processes, composed of multiple repeating modules, is considered. In this framework, the concept of modular hybrid ABM–DES technique is introduced to demonstrate a novel simulation method using a dynamic system of parallel multi-agent discrete events. In this context, to create a modular model, the stochastic finite dynamical system is extended to allow the description of discrete event states inside the agent for manufacturing repeating modules (meso level). Moreover, dynamic complexity regarding uncertain processing time and resources is considered. This framework guides the user step-by-step through the system design and modular hybrid model. A real case study in the cell and gene therapy industry is conducted to test the validity of the framework. The simulation results are compared against the data from the studied case; excellent agreement with 1.038% error margin is found in terms of the company performance. The optimal resource planning and the uncertainty of the processing time for manufacturing phases (exo level), in the presence of dynamic complexity is calculated
Advancement in robot programming with specific reference to graphical methods
This research study is concerned with the derivation of advanced robot
programming methods. The methods include the use of proprietary
simulation modelling and design software tools for the off-line
programming of industrial robots. The study has involved the generation
of integration software to facilitate the co-operative operation of these
software tools.
The three major researcli'themes7of "ease of usage", calibration and the
integration of product design data have been followed to advance robot
programming. The "ease of usage" is concerned with enhancements in the
man-machine interface for robo t simulation systems in terms of computer
assisted solid modelling and computer assisted task generation.
Robot simulation models represent an idealised situation, and any off-line
robot programs generated from'them may contain'discrepancies which could
seriously effect thq programs' performance; Calibration techniques have
therefore been investigated as 'a method of overcoming discrepancies
between the simulation model and the real world.
At the present time, most computer aided design systems operate as
isolated islands of computer technology, whereas their product databases
should be used to support decision making processes and ultimately
facilitate the generation of machine programs. Thus the integration of
product design data has been studied as an important step towards truly
computer integrated manufacturing.
The functionality of the three areas of study have been generalised and
form the basis for recommended enhancements to future robot programming
systems
Product life cycle information management in the electronics supply chain
Information availability and data transparency are key requirements from manufacturers when
supporting products throughout the life cycle, for example when implementing product service
systems. The application of embedded wireless technologies into printed circuit boards (PCBs) can
help bridging current knowledge gaps and to minimise both technical and financial risk through
reduced product downtime, improved quality of tracking and enhanced end-of-life decision
making. The application of embedded RFID into PCBs for life cycle monitoring of electronic
products to support Product Service Systems is discussed in this paper
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