Production Stoppages Research Articles

Container fleet-sizing for part transportation and storage in a two-level supply chain

This research addresses the fleet-sizing of containers that are used for the protection, transportation, and storage of parts between a component plant and multiple assembly plants. These containers are needed for the storage of completed parts as they are produced, and also for storage of parts as they are used in assembly. The containers are reusable, expensive, occupy a large amount of space when empty or full, and are required to maintain production. An analytical model is developed for the minimum container fleet size that results in no production stoppages due to lack of containers assuming no system variability. The model considers the discrete nature of part production and shipping as well as differences in available production and transportation time. The model is shown to be accurate and provides insight into the factors that affect container fleet size and production stoppage trade-offs.

The physical ability of women in mining: Can they show muscle?

For many years, mining has been considered the foundation of the South African economy. Although the mining industry in South Africa is currently under considerable pressure and experiences various challenges, including escalating operational costs, electricity tariff increases, safety-related issues and associated production stoppages, poor productivity, labour unrest, and reduced demand both globally and domestically, it remains a key contributor to the national economy and development of the country (IDC, 2013, p. 9). Until 1994, women were legislatively prohibited from meaningful participation in the mining industry and were denied access to skills and jobs, self-employment, and entrepreneurship. The newly elected democratic government in 1994 initiated substantial socio-political and economic transformation in South Africa. Nearly every sector in the country was transformed and re-shaped, primarily through sector-specific legislation, but also through negotiations between government, industry, and labour unions to create and refine the so-called sector charters, which included the Mining Charter. The vision of the new regime, the African National Congress (ANC), was to ‘transfer power to the people and transform society into a non-racial, non-sexist, united, democratic one, and change the manner in which wealth is shared, in order to benefit all the people’ (ANC, 2007). Transformation in the South African mining industry is governed by the provisions of the Mineral and Petroleum Resources Development Act, No. 28 of 2002 (RSA, 2002), which was promulgated and implemented on 1 May 2004, and the Broadbased Socio-economic Empowerment Charter for the South African Mining Industry (RSA, 2004) (hereinafter referred to as the Mining Charter), which was signed in October 2002 and formally published on 13 August 2004. The broad objectives of the Act and the accompanying Mining Charter (and the amended Charter) are to rectify previous inequalities and disadvantages in the mining sector and to ensure equity, accessibility, and sustainability in the industry. The Act and the Charter make specific provisions for the inclusion of women in core mining activities, in terms of which the industry was supposed to reach a quota of 10% women in core mining activities by 2009. Core mining activities include, among other activities, mining, metallurgy, engineering, and geology (Harmony Gold Mining Company, 2008, p. 32). In 2009, the Department of Mineral Resources conducted a thorough impact assessment to determine the progress made The physical ability of women in mining: can they show muscle?

Application of Slantlet Transform Based Support Vector Machine for Power Quality Detection and Classification

Concern towards power quality (PQ) has increased immensely due to the growing usage of high technology devices which are very sensitive towards voltage and current variations and the de-regulation of the electricity market. The impact of these voltage and current variations can lead to devices malfunction and production stoppages which lead to huge financial loss for the production company. The deregulation of electricity markets has made the industry become more competitive and distributed. Thus, a higher demand on reliability and quality of services will be required by the end customers. To ensure the power supply is at the highest quality, an automatic system for detection and localization of PQ activities in power system network is required. This paper proposed to use Slantlet Transform (SLT) with Support Vector Machine (SVM) to detect and localize several PQ disturbance, i.e. voltage sag, voltage swell, oscillatory-transient, odd-harmonics, interruption, voltage sag plus odd-harmonics, voltage swell plus odd-harmonics, voltage sag plus transient and pure sinewave signal were studied. The analysis on PQ disturbances signals was performed in two steps, which are extraction of feature disturbance and classification of the dis- turbance based on its type. To take on the characteristics of PQ signals, feature vector was constructed from the statistical value of the SLT signal coefficient and wavelets entropy at different nodes. The feature vectors of the PQ disturbances are then applied to SVM for the classification process. The result shows that the proposed method can detect and localize different type of single and multiple power quality signals. Finally, sensitivity of the proposed algorithm under noisy condition is investigated in this paper.

The Effects of Piezoelectric Ceramic Dissipation Factor on the Performance of Ultrasonic Transducers

The dissipation factor (DF) is an important material property of piezoceramics that governs the amount of self-heating under resonant conditions; it essentially quantifies a particular material type for either an actuator or resonator application: high DF materials with typically higher output (d33) are better for actuators, whereas low DF materials with typically lower d33 are better for resonators. Transducer designers must often compromise between mechanical output and DF in the selection of piezoceramics for power ultrasonic applications, and abnormally high DF is one of the main causes of production stoppages. In theory DF is simply the current/voltage phase deviation from an ideal capacitor at 90° (a.k.a. tan(δ) or dielectric loss). Abnormally high DF is typically caused by moisture absorption due to poor ceramic porosity, which causes voltage leakage effects; e.g., seen in transducer production when setting piezo stack preload. Corresponding large increases in capacitance can also be associated with poor porosity, which is counterintuitive unless there is moisture absorption or electrode wicking. This research investigates the mechanisms for abnormally high DF in peizoceramics, and its corresponding effect on transducer performance. It investigates if DF is only affected by the bulk dielectric properties of the piezoceramics (e.g. porosity), or is also influenced by non-uniform electric field effects from electrode wicking. It explores if higher DF ceramics can affect transducer displacement/current gain stability via moisture expulsion at higher drive levels. The investigation focuses solely on the common PZT8 piezoelectric material used with welding transducers for semiconductor wire bonding. Transducers are built with both normal DF peizoceramics, and those with abnormally high DF ceramics which caused production stoppages. Several metrics are investigated such as impedance, displacement gain and capacitance. The experimental and theoretical research methods include Bode plots, SEM cross-sections, Archimedes method, equivalent circuits, laser vibrometry and finite element analysis.

A survey on the adoption of lean practices in the process sector of India with a comparison between continuous and batch process industries

Abundance of literature is available about lean implementation in discrete manufacturing. However, for process industries it is still doubtful which lean practices are adoptable and useful. This paper aims to investigate the highly used and rarely used lean practices in Indian process industries. This exploratory study demonstrates the parts of the results of a comprehensive survey. The survey questionnaire was sent to 500 Indian process industries and 105 usable responses were received. Results illustrate an extensive use of 5S, work standardisation, new equipment and technology, TPM and quality management program in Indian process industries. However, use of lean tools such as Kanban, pull production and automatic line stoppage is not common in Indian process industries. Batch process industries have adopted lean practices more formally and comprehensively than continuous process industries. Finally, there is considerable distinction regarding use of lean practices among different types of process industries according to the product. The paper may help the academicians and practitioners from process industry by providing important implications about lean implementation.

Modeling and automatic calculation of restart states for an industrial windscreen mounting station

The production in an automated manufacturing system will not always progress as intended. A wide variety of possible faults may cause errors that lead to an unsynchronization between the control system and the physical system that consequently lead to production stoppages. The common industrial practice to deal with such non-intended progress is to extend the control system with tailor- made solutions to account for errors. This extension is both time consuming and there is no guarantee that all relevant errors are handled.This paper models the control system to enable automatic derivation of restart states applied to an existing station for automatic mounting of windscreens onto car bodies. These restart states are states in the control system where it is correct to resynchronize the control and the physical systems so that the automated production can be resumed. This aids the preparation phase by letting the developer focus on modeling the nominal production and on specifying (un-)desired behavior during the restarted production, and then automatically retrieve the restart states for all control states. The online restart process is then reduced to a semi-automatic process where an operator can be supported with instructions for how to correctly resynchronize the control and the physical systems in a selected restart state.

Fast Production Recovery of a Typhoon-Damaged Oil Field in the South China Sea

Summary The Huizhou oil field is located at the Pearl River mouth in the continental-shelf region of the South China Sea, with an average water depth of approximately 117 m. The oil field's main facilities include eight fixed-jacket platforms, two subsea-production wellheads (HZ32-5 and HZ26-1N), and one floating production, storage, and offloading (FPSO) vessel (Nanhai Faxian). Fig. 1 illustrates the general layout of the field. The peak daily oil production is approximately 70,000 BOPD. In September 2009, after a strong typhoon (Koppu) passed over this oil field, the FPSO vessel's permanent mooring system was seriously damaged. All production risers connected to the FPSO vessel's turret were ruptured, and production was forced to shut down. To resume production in a fast-track manner, several engineering cases were studied. Finally, the concept of using a dynamic-positioning (DP) FPSO vessel to temporarily resume production was selected. Detailed design and operability analysis was performed by the owner of the DP-FPSO vessel, and various flexible pipes and other materials were sourced quickly in local and international markets. The offshore installation took place throughout the harsh winter monsoonal season from November 2009 to February 2010. Finally, the field was brought back into production after 5.5 months of production stoppage. The DP-DPSO system operated for more than 18 months and proved safe and effective. This was world record time for an FPSO vessel operated in DP mode.

Motor current signature analysis for gearbox health monitoring: Experiment, signal analysis and classification

Preventing downtimes in machinery operation is becoming fundamental in industrial standards. The most common strategy to avoid costly production stoppages is the preventive maintenance, combining it with reactive maintenance in detected malfunctions. Condition-based maintenance can reduce costs, and help maintaining the quality of the produced goods. Gearboxes, as crucial elements in industrial machinery, are conventionally monitored using accelerometers, which are expensive and can be hard to install in place to provide useful information.Motor current signature analysis overcomes these inconveniences. This analysis technique provides a non-intrusive method, and it is based on readily available signals. Changes in the input voltages are related with variations of the speed and/or load of the electric motor. The health state of the gearbox can be examined through an exhaustive analysis of the input currents.A gear prognosis simulator (GPS) test bench has been used to perform an extensive experimentation campaign. This test bench is particularly convenient due to the flexibility it provides. Different sets of sensors can be placed in different positions, and multiple combinations of speeds and loads can be established. Three damage categories in the gears have been analyzed, high damage, moderate damage and little damage. The test parameters have been selected to simulate the working conditions of electromechanical actuators and machine tools. Constant speed and transient tests have been performed. In the transient tests, fast speed changes are performed to produce acceleration, to investigate the concomitant changes produced in the signal. The analysis has been performed in both the time and the frequency domain, and complementarily, using the wavelet decomposition. The results obtained allow discerning the different type of defects on the gears, thus allowing detecting the different fault conditions and enabling the assessment of the health state of the gearbox.

10.5937/zeint24-6596 = Detection of shorted turns on rotor poles in hydrogenerators using artificial neural networks

Early diagnosis of faults that might occur in industrial processes makes it possible to perform important preventative actions and therefore avoid the heavy economic losses involved in production stoppages and the replacement of elements and parts. The main idea of detecting shorted turns on rotor poles in hydrogenerators using artificial neural networks is to generate signals that reflect inconsistencies between nominal and faulty system operating conditions. Two types of nonlinear autoregressive networks with exogenous inputs (NARX) are used. In both cases one can successfully detect shorted turns on rotor poles.

Examining the possible influence of societal violence on governance effectiveness in South Africa

This paper examines the possible influence of violent protests on the effectiveness of governance in South Africa. South Africa continues to experience huge number of labour as well as popular municipal service delivery protests. The popular social view with ensuing protests has often pointed at governance inefficiency as the cause of violent protests. This paper adopts a slightly different view in its analysis of violent protests and instead looks at possible influence of violence as possible instigator of ineffective governance. The paper is conceptually rooted in reviews – combined with simple regression test of possible relationship between violent protest and governance effectiveness. The authors also present an examination of probable relationship between violent protests and governance effectiveness using observation of macro-economic data trends from the World Bank. The findings reveal a probable weakening in governance effectiveness or its perception thereof as a result of violent protests. Amongst others, violent protests produces a psyche of perpetual victimhood that leads to further violence resulting in less value attached to lives, destruction of economic property, increases pollution, production stoppages for goods and services and in turn depletes government revenue generation and frustrates international investors. We postulate that under condition explained above, government effectiveness in managing public resources becomes weakened and may lead to wastage and inefficiency as the resources and revenues employed in controlling violent protests are unplanned and do not often lead to constructive and sustainable public policy. We suggest that this condition therefore may result in reduction in economic growth which in turn perpetuates the same weaknesses that led to society protests and violence

Simulation of the solidification of the melt in the Vanyukov furnace in the case of emergency stoppage

A mathematical model of the Vanyukov furnace, which makes it possible to predict the behavior of an object in the emergency operational mode (upon the disconnection of the oxygen supply) and develop an effective system of additional heating which damps the consequences of the emergency mode and lowers the costs for the renovation of the furnace operation, is created. It is shown how solidification upon cooling the furnace with time is simulated using the enthalpy and porosity method. The mathematical model is adopted for existing production conditions, which are weakly defined. The energy characteristics of the mode for the solidifying furnace bath, which ensures its holding for a long time in the ready state to rapid firing, are found. Thus, the problem of excessively expensive furnace firing after prolonged production stoppage is solved in the conjugated statement with a calculation of the heating system of the overbath space.

Controle on-line da taxa média de defeitos por item produzido numa produção finita

Este trabalho propõe uma abordagem para monitoramento da taxa média de defeitos por item produzido numa produção finita ou encomenda de N itens. A cada ciclo de m itens produzidos, inspecionam-se os últimos r itens. Em cada item inspecionado conta-se o número de defeitos e cada item é classificado como aprovado se o número de defeitos satisfizer o critério do limite de controle. Se todos os r itens forem aprovados, a produção continua, caso contrário interrompe-se a produção à procura de causas especiais. Os itens inspecionados são descartados somente quando há parada no processo. Após a produção de N itens, um lote adicional será produzido para completar a quantia encomendada, mas esses não passarão por inspeção. Será utilizada uma cadeia de Markov finita de estados discretos para determinar as probabilidades de mudança de estado. Elas são utilizadas nas expressões de custo para determinar a estratégia ótima de monitoração, que será obtida através da otimização de três parâmetros: intervalo amostral (m), tamanho da amostra retrospectiva (r) e o limite de controle (LC). Os parâmetros serão obtidos através de busca direta, de forma que se minimize a expressão do custo médio por item produzido. Um exemplo numérico ilustra a proposta.

Advanced Supply Chain Information for Rule-Based Sequence Adaptions on a Mixed-Model Assembly Line with Unreliable Just-In-Sequence Deliveries

The proliferation of just-in-sequence (JIS) deliveries has raised the vulnerability of assemblies to costly production stoppages or rework due to missing components. Through a comprehensive real-time supply chain monitoring systems, these supply issues can be detected early and affected orders removed from planned assembly sequences in time to avoid production disturbances. Using simulation analysis, this paper explores the impact of unreliable JIS deliveries and the mitigation potential of transparent supply chains that allow a rule-based order resequencing on a mixed-model assembly line. The results indicate that (i) rework due to unreliable JIS deliveries can be eliminated and (ii) the trade-off between schedule nervousness and optimality can be balanced, making the proposed rule a feasible approach.

An Effort to Establish Correlations between Brazilian Crude Oils Properties and Flow Assurance Related Issues

Flow assurance is a multidiscipline process involving sampling, laboratory analysis, and production and facilities engineering to ensure uninterrupted optimum well productivity. Laboratory testing provides necessary data to assess the flow assurance risk because it defines phase behavior and the properties of the waxes, asphaltenes, emulsions and hydrates known to be principal causes of flow problems. In deep- and ultra-deepwaters scenarios the precipitation, deposition, and gelling of organic solids in hydrocarbon fluids constitute critical production concerns. Understanding the crude oil behavior can help to avoid high costs resulting from production reductions or stoppages or, conversely, from system overdesign. This paper shows an effort to establish correlations between Brazilian crude oils properties and flow assurance related issues.

Quebec Pharmacists and Physicians Call for Legislative Changes to Combat Drug Shortages in Canada

Drug manufacturers in Canada should be legally required to secure several supply sources for raw materials and several manufacturing sites when seeking approval to market an essential drug — according to a joint pharmacy-medical working group in Quebec. The group also calls for legislation that would force pharmaceutical companies to give 1-year's notice before any voluntary production stoppage. The Working Committee on Drug Shortages was created by the Quebec pharmacy college — l'Ordre des pharmaciens du Quebec (OPQ) — and began its work in March 2011. Its mandate was to assess the causes of drug supply disruptions and to propose solutions that could become part of a national strategy. The committee included representatives from the Association quebecoise des pharmaciens proprietaires (AQPP) and the Association des pharmaciens des etablissements de sante du Quebec (APES), as well as from the physicians' college, the College des medecins du Quebec (CMQ). In a report released April 16, 2012, the committee outlined 9 recommendations aimed at securing the supply of pharmaceutical products. “The growing number of shortages, along with their consequences for patients, calls for an overall analysis of the cause and the implementation of concrete solutions for preventing rather than enduring supply disruptions,” OPQ president Diane Lamarre said in a news release. Drug shortages have plagued the Canadian system for at least the past 2 years, but the situation has recently worsened. In February, Sandoz Canada announced it would immediately stop production of certain drugs at its Boucherville, Quebec, plant — due to an order from US regulators to improve quality-control processes. Sandoz is the sole supplier to Canadian hospitals of 90% of all injectable drugs. Mandating a 1-year notice period “is crucial so that we can come up with viable alternative solutions, whether finding new supply sources or identifying substitute medications, for example,” said Charles Fortier, president of the APES.

Flow Assurance Study for Waxy Crude Oils

In subsea environments, wax-phase separation, deposition, and gelling constitute an important concern in production operation/activities. Understanding the crude oil wax-phase behavior can help to avoid the high costs resulting from production reduction or stoppage in the field operations to mitigate these effects. Conversely, expenses arising from production system overdesign may also be prevented. In this context, two waxy crude oils from different Brazilian fields were selected to be characterized according to Petrobras technical specification for flow assurance requirements. These light crude oils A and B have similar chemical characteristics of saturates, aromatics, resins, and asphaltenes (SARA) analysis, but crude oil A has a wax appearance temperature 15 °C higher than crude oil B. Despite having a density around 29° American Petroleum Institute (API), for a rheological point of view, crude oil B has a viscosity about half that of crude oil A at 20 °C. In addition, crude oil B dehydrated exhibits ...

Cost reduction of subsea gas production systems using emerging hydrate remediation technology

Gas flowlines are presenting flow assurance challenges in hydrate management resulting from low ambient seawater temperatures in an increasing number of deepwater developments. When the equilibrium hydrate temperature of the produced fluid is above the minimum seabed temperature, and the hydrate inhibition system fails, there is a risk of hydrate blockage in the subsea system. The industry-preferred approach for hydrate blockage remediation is dual sided depressurisation (DSD). The objective is to depressurise the flowline below hydrate onset conditions, thus allowing hydrate dissociation and safe disposal of the gas inventory. This is generally performed by one of two methods: installation of a dual flowline system for facility-based depressurisation (CAPEX impact) or by connecting a mobile offshore drilling unit (MODU) to an appropriate wellhead or christmas tree (XT) to allow simultaneous depressurisation at the MODU and the facility (OPEX impact). It is recognised that both methods incur significant costs. Typically the cost, schedule and availability uncertainties of bringing in a MODU to solve these production stoppages are too high. Consequently, subsea developments often select the increased CAPEX option. An optimisation of the MODU-based intervention method is the subject of this paper. The feasibility of using a lightweight intervention vessel (e.g. an offshore support vessel) in place of the MODU is investigated. In discussing this optimisation, this paper also presents an introduction to hydrate remediation theory, some practical challenges, case studies and vessel requirements.

Formulation and a Simulation-Based Algorithm for Line-Side Buffer Assignment Problem in Systems of General Assembly Line With Material Handling

In systems of general assembly line with material handling, line-side buffers need to be carefully assigned to a limited number of material delivers (drivers) for part delivery to avoid production stoppage due to material shortage. Such a problem is referred to as line-side buffer assignment problem (LBAP). In this paper, we focus on fixed zoning version of LBAP. We formulate the problem, prove its NP-hardness, and propose an algorithm based on two structural characteristics of the LBAP problem-one being the analogousness between our problem and the parallel machine scheduling (PMS) problem and the other being the monotonicity of the system throughput in the course of assigning line-side buffers to drivers. The developed algorithm globally converges with probability one when there exist feasible assignments. The algorithm is tested on a real system, and the results show that it is effective for solving the LBAP problem.

Detecting a change by a single neuron

Event Abstract Back to Event Detecting a change by a single neuron Hideaki Kim1*, Barry J. Richmond2 and Shigeru Shinomoto1 1 Kyoto University, Japan 2 NIMH/NIH/DHHS , Laboratory of Neuropsychology, United States Detecting a change in state of a dynamical process from observing noisy signals is a well-known and difficult statistical problem that has practical applications in places such as manufacturing to detect substandard products [1,2]. Late detection increases inferior goods, whereas false alarms lead to unnecessary production stoppages. There is a parallel in animal behavior. It would be advantageous for individuals to detect subtle changes in the environment as early as possible to avoid predators or to locate prey without incurring a high false alarm rate. In practice, animals seem to detect changes even in weak sensory signals reliably and efficiently [3]. These signal changes occur trains of irregularly timed neuronal spikes. Although the physiological mechanisms underlying this apparently efficient statistical computation have not been identified yet, recent studies show that even single neurons could detect changes in the rate of an incoming spike train [4,5,6]. To investigate the potential for a single neuron to detect a change point, we carry out a systematic analysis using a single leaky integrate-and-fire model. By combining a Bayesian criterion [7] for measuring the quality for a change-point detector and the first passage time of Ornstein-Uhlenbeck process, we develop a method for optimizing the neuronal parameters, including the membrane time-constant and the threshold, given initial and final rates of an incoming spike train. We find that a single leaky integrate-and-fire neuron can achieve performance close to that of Bayes-optimal detection algorithm [8]. Given a reasonable number of synaptic connections and the rate of the input spike train, the values of the membrane time-constant and the threshold that maximize change point detectability are close to those seen in biological neurons, suggesting that biological neurons could be acting as change point detectors.

Concurrent Optimization of Crescent Bond Pull Force and Tail Breaking Force in a Thermosonic Cu Wire Bonding Process

In conventional wire bonding process optimization, the crescent bond is tested by destructive pulling the loop and measure the pull force (PF) required to break the bond. While this method assures the final quality, it does not necessarily minimize production stoppages which can reduce throughput significantly. Many stoppages are caused by short-tail and tail-lift errors which in turn are caused by reduced tail bond strength. The tail breaking force (TBF) is a measure for tail bond strength. A consistent tail breaking operation is needed for robust Cu wire bond production with little operator assistance required to restart stopped machines. We report the concurrent (simultaneous) optimization of PF and TBF using standard pull testing and a method that directly measures the tail bond strength in-process, respectively. The example process uses standard 25-mum-diameter Cu wire on standard Ag-plated leadframe diepads and wire loops oriented perpendicular to the ultrasonic horn. The optimization consists of (1) finding the factors to obtain a symmetrical bond shape, (2) choosing fixed values for bond time (25 ms) and heater stage temperature (220degC), and (3) adding the new optimization step of maximizing the TBF by iteratively optimizing the impact force (IF), bonding force (BF), and ultrasound (US) parameters. Among these parameters, the US and BF are the most significant. A process window (PW) is defined as the set of US/BF parameter combinations that result in a response being inside a previously defined range. PWs for PF and TBF are determined and compared with each other. There is only a partial overlap of these PWs. To increase the process capability index (cpk) for TBF, it is recommended to first carry out conventional PF optimization followed by a minimization of the bonding force parameter to the lowest value still fulfilling the PF cpk requirement.