Assessing capacity scalability policies in RMS using system dynamics

This paper presents a model for assessing different capacity scalability policies in Reconfigurable Manufacturing System (RMS) for different changing demand scenarios. The novelty of this approach is two fold: (1) it is the first attempt to explore different capacity scalability policies in RMS based on multiple performance measures, mainly scaling rate, Work In Process level, inventory level and backlog level; and (2) the dynamic scalability process in RMS is modeled for the first time using System Dynamics. Different policies for capacity scalability for various demand scenarios were assessed. Numerical simulation results obtained using the developed capacity scalability model showed that the best capacity scalability policy to be adopted for RMS is dependent on the anticipated demand pattern as well as the various manufacturing objectives. The presented assessment results will help the capacity scalability planners better decide the different tradeoffs between the competing strategic and operational objectives of the manufacturing enterprise, before setting the suitable capacity scalability plan parameters

A multiple performance analysis of market-capacity integration policies

A model that uses simulation augmented with Design of Experiments (DOE) is presented to analyse the performance of a Make-to-Order (MTO) reconfigurable manufacturing system with scalable capacity. Unlike the classical capacity scaling policies, the proposed hybrid capacity scaling policy is determined using multiple performance measures that reflect cost, internal stability and responsiveness. The impact of both tactical capacity and marketing policies and their interaction on the overall performance was analysed using DOE techniques and real case data. In addition to the different insights about the trade-offs involved in capacity planning decisions, the presented results challenged the conventional capacity planning wisdoms in MTO about the negative role of the capacity scalability delay time. Finally the analysis demonstrated the importance of inter-functional integration between capacity and marketing policies

Variety and volume dynamic management for value creation in changeable manufacturing systems

In today’s uncertain market and continuously evolving technology, managing manufacturing systems are more complex than ever. This paper studies the dynamics of managing variety and volume to enhance value creation in manufacturers implementing system-level advanced and automated manufacturing technology (AAMT). The demand is composed of heterogeneous customers who make purchasing decisions depending on the variety levels and lead times of the firm’s product offerings. The cost structure adopted calculates profit as the difference between customer value creation rate (VCR) and costs associated with the process of creating this value. Reported results contribute to the variety and volume management literature by offering analytical clarity of factors affecting product platforms and capacity scalability management for systems with AAMT. In addition, insightful answers to the trade-offs between profit maximising market coverage and investments, smoothing demand policies and system stability for this type of environment are presented. Furthermore, the value of market information in deciding the industrial technology investment and also the impact of product life cycle on the same investment is captured

Modelling and analysis of dynamic capacity complexity in multi-stage production

The uncertainty associated with managing dynamic capacity problem is the main source of its complexity. This article presents a system dynamics approach to model and analyse operational complexity of dynamic capacity in multi-stage production. The unique feature of this approach is that it captures the stochastic nature of three main sources of complexity associated with dynamic capacity. These are the demand, internal manufacturing delay and capacity scalability delay. The developed model was demonstrated by an industrial case study of multi-stage printed circuit board assembly line. The analysis of simulation experiments showed that ignoring complexity sources can lead to wrong decisions concerning both scaling levels and backlog management decisions. In addition, a general trade-off between the controllability and complexity of the dynamic capacity was illustrated. Finally, comparative analysis of the effect of each of these sources on the complexity level revealed that internal delay has the highest impact on dynamic capacity efficiency. Guidelines and recommendations for better capacity management and reduction of its complexity are presented

Anesthetic management of a patient with hypertrophic obstructive cardiomyopathy undergoing modified radical mastectomy.

Hypertrophic obstructive cardiomyopathy (HOCM) is a rare genetic disorder characterized by left ventricular outflow tract (LVOT) obstruction. Clinical presentation ranges from absence of symptoms to sudden death. Our 60 year old Patient scheduled for left modified radical mastectomy had HOCM since seventeen years with severe LVOT obstruction and mitral regurgitation. An implantable cardioverter defibrillator (ICD) and permanent pacemaker (PPM) was inserted 15 months earlier for ventricular tachycardia. Anesthetic management of these Patients presents considerable challenges and requires maintenance of desired hemodynamic parameters and management of specific complications. Factors like tachycardia, hypovolemia, vasodilation and increased cardiac contractility leads to exacerbation of the obstruction. In our Patient there was the additional consideration of the ICD which required to be turned off during surgery with full provision for external defibrillation. We managed to successfully maintain the desired hemodynamics throughout the surgery and the Patient was discharged home on the seventh postoperative day

Health Beliefs Related to Diabetes Mellitus Prevention among Adolescents in Saudi Arabia

 Objectives: The incidence of type 2 diabetes mellitus (T2DM) is growing rapidly in the Saudi population. The purpose of this study was to assess the constructs of the health belief model (HBM) as they relate to T2DM lifestyle and prevention behaviours among adolescents. Methods: A cross-sectional study was conducted between May and October 2013 among 426 non-diabetic secondary school students from randomly selected schools in Riyadh, Saudi Arabia. An Arabic version of an adapted English language questionnaire was used to assess knowledge and attitudes related to the severity and prevention of T2DM. A preventative behaviour assessment was also conducted to assess physical activity and dietary habits. Results: The majority of the students (63.4%) had at least one diabetic family member. Obesity was more frequent in males compared to females (P = 0.013). Awareness about the importance of maintaining a healthy body weight to prevent T2DM was lower in males than females (P = 0.037), although males engaged in routine exercise more often (P = 0.001). Males were less likely than females to recognise the risks for T2DM, including obesity (P = 0.030), heredity (P = 0.013) and high fat intake (P = 0.001). Conclusion: An alarmingly high number of Saudi students were unaware of T2DM severity and associated risk factors. Female students were more aware of the benefits of T2DM preventative lifestyle behaviours than males, although males engaged in routine exercise more often. Raising adolescents’ awareness about the primary prevention strategies for T2DM should be a public health priority in Saudi Arabia. The HBM could inform further research on diabetes prevention among Saudi adolescents

Novel Adsorbent For Industrial Wastewater Treatment Applications

In this study, the hydroxyapatite powder is investigated for both of methylene blue and thymol blue in aqueous solution. The physical and chemical properties of the adsorbent were evaluated systematically using the different techniques including Microsoft Excel programming, linear regression model and also the coefficient of determination. Batch adsorption experiments were conducted to determine the effect of contact time, solution pH, initial dye concentrations, and also the adsorbent dosage on adsorption. The adsorption kinetic parameters confirmed the better fitting of pseudo-second order kinetic model for both of methylene blue and thymol blue. The isotherm data of methylene blue and thymol blue could be well described by the Freundlich isotherm model which means the adsorption is multilayer adsorption with non-uniform distribution of adsorption heat and affinities over the heterogeneous surface. The maximum adsorption capacity (KF) of methylene blue and thymol blue is found to be 0.2736 (L/mg) and 11.18407 (L/mg) respectively. The high specific surface area and the porous structure with some acidic functional groups on the surface were obviously responsible for high dyes adsorption onto hydroxyapatite (HA). Adsorption kinetics data were modeled with the application of Pseudo first order, Pseudo second order and Intraparticle diffusion models. The results revealed that the Pseudo second order model was the best fitting model. Which means that, the adsorption mechanism followed two stages in which the first one was fast and the other was slower step. Which means the adsorption of dye molecules was limited by intra particle diffusion and film diffusion, as well as the adsorption rate in both of adsorption system are depends only on the slower step. The Boyd plot exposed that the intra-particle diffusion was the rate controlling step of the adsorption process of both of methylene blue and thymol blue molecules by HA powder. However, the adsorption of methylene blue molecules (basic solution) using of HA as adsorbent particles is found to be extremely preferable than thymol blue molecules

Primjena umjetne toplinske stimulacije kao novi pristup za indukciju tendinopatije u magaraca

Animal models for tendonitis are essential for studying the disease’s mechanism and pathogenesis, and evaluating different therapeutic protocols. The temperature seems to play a significant role in tendinitis initiation. The aim of this study was the generation of a novel, safe and cheap tendinitis model, and validation of its reliability. The effect of microwave diathermy (30 watts for 30 min) on the flexor tendons of donkeys as animal models was investigated after 15, 30 and 60 days. The evaluation was based on geometric analysis, ultrasonography, histomorphometric analysis and scanning electron microscopy (SEM). Microwave diathermy was capable of successfully inducing well-defined lesions in the superficial digital flexor tendon (SDFT) as well as the deep digital flexor tendon (DDFT). The results showed that all the animals exhibited signs of lameness, starting on day 15 and reaching on maximum on day 30. A significant increase in limb circumference was also detected on day 30 (P<0.05). Furthermore, the geometrical analysis of the proportion of induced lesion (PIL) in correlation with the tendon diameter, revealed that PIL was at the maximum width on day 30 (20.6 ± 1.2% for SDFT and 15.7 ± 0.7% for DDFT), as detected by ultrasound. Moreover, a high number of rounded tenocytes, bleeding, severe matrix disruption, and an increase in fiber thickness were detected by histomorphometric analysis. Also, the matrix alignment was severely disrupted in both SDFT and DDFT by day 30, as confirmed by SEM. In conclusion, using microwave diathermy for induction of tendonitis in donkey is a reliable, minimally invasive, and cost-effective tendonitis model.Uporaba životinjskih modela je neophodna za proučavanje mehanizma bolesti, patogeneze i za procjenu protokola liječenje tendinitisa. Čini se da temperatura igra značajnu ulogu pri nastajanju tendinitisa. Cilj istraživanja bio je stvaranje novog, sigurnog i jeftinog modela za proučavanje tendinitisa te potvrda njegove pouzdanosti. Učinak mikrovalne dijatermije (30 vata tijekom 30 min) na tetive fleksora u magaraca kao životinjskih modela istraživan je nakon 15, 30 i 60 dana. Procjena se temeljila na geometrijskoj analizi, ultrazvuku, histomorfometrijskoj analizi i skenirajućoj elektronskoj mikroskopiji (SEM). Mikrovalna dijatermija uspješno je inducirala dobro definirane lezije u površinskoj digitalnoj tetivi fleksora (SDFT) kao i dubokoj digitalnoj tetivi fleksora (DDFT). Rezultati su pokazali da su sve životinje pokazivale znakove hromosti, počevši od 15. dana i dostižući maksimum 30. dana. Također, 30. dana je uočeno znakovito (P<0,05) povećanje opsega ekstremiteta. Nadalje, uporabom ultrazvuka i primjenom geometrijske analize udjela inducirane lezije (PIL) u korelaciji s promjerom tetive, ustanovljeno je da je PIL bio maksimalne širine 30. dana (20,6 ± 1,2% za SFT i 15,7 ± 0,7% za DDFT). Osim toga, histomorfometrijskom analizom otkriven je povećan broj zaobljenih tenocita, krvarenje, teži poremećaji u matriksu i povećanje debljine vlakana. Do 30. dana, SEM analiza je pokazala izražene poremećaje u poravnavanju matriksa i u SDFT i u DDFT. Zaključno, primjena mikrovalne dijatermije za indukciju tendinitisa kod magaraca je pouzdan, minimalno invazivan i troškovno učinkovit životinjski model za proučavanje ove bolesti