Effect of monosodium glutamate additive on the performance of dialysis membrane

A novel dialysis membrane with monosodium glutamate (MSG) as an additive has been fabricated and its performance evaluated in terms of urea clearance. Nine formulations of casting solutions had been designed with 20% cellulose acetate, and different ratio of formic acid/MSG. The result shows that MSG based membrane with the 6 wt% of MSG, achieved the best urea clearance, 53.20%. SEM images illustrated that the increment of MSG in casting solution tend to promote macrovoids formation and finally transit to finger like structure. However, when the amount of MSG is further increased beyond 6 wt%, the urea clearance reduced and the macrovoids structure disappeared. Thus, enlarged finger like structure favors the dialysis process

Application Of Counter-current Fluidized Cascade In Flotsam-rich Mixtures

The counter-current gas fluidized cascade is a novel pneumatic device for the separation of mixed granular solids according to density and size difference. The study presented here is restricted to the application of the cascade in flotsam-rich binary solids systems.;The purpose of this study was to investigate the effect of the density difference and size distributions of the two solids, the height and speed of the paddles, the fluidization velocity and feed and product withdrawal rates on the separation performance of the cascade. It was observed that while a significant density difference would usually result in strong segregation in the simple fluidized bed, the cascade performance was less predictable. Separation efficiency appeared to deteriorate as the mean particle size of the components decreased. The present results indicate the importance of paddle height, paddle speed and fluidization velocity on separation efficiency. The experimental data was subjected to a multiple regression analysis. Additionally, a theoretical model was presented to describe the performance of the cascade under total reflux conditions. The dependence of diffusivity on the horizontal convective velocity of the fluidized solids was incorporated into the model. Agreement between the model and experimental results is reasonable.;Of the various solids systems investigated, the natural coal system is of industrial importance. The present study demonstrated the potential of the cascade as a simple and inexpensive device in coal beneficiation, despite the limitation on the purity of the product imposed by the degree of liberation of pyrite and ash from the coal matrix. Experiments with the natural coal system have also demonstrated that the separation effectiveness of the cascade could be improved by a multi-pass process in which the products and rejects were reprocessed in subsequent passes in the cascade.;The present work should be viewed as a first attempt to investigate the performance of the cascade in the separation of flotsam-rich solids systems. Continuation of the present experimental program as well as further theoretical development is recommended for a more thorough understanding of the cascade

Response surface methodology approach to study the influence of PEG and water in cellulose acetate dialysis membranes

Flat sheet asymmetric dialysis membranes were fabricated using phase inversion method from polymer solution consisting of cellulose acetate, acetic acid, polyethylene glycol (PEG) and distilled water. The effect of acetic acid/PEG ratio and the distilled water content in the dialysis membrane were being investigated with respect to the urea clearance performance. Response surface methodology (RSM) was used to design the experiments and analysed the results obtained. The analysis revealed that the significant factor that affects the cellulose acetate dialysis membrane performance in terms of urea clearance is the ratio of acetic acid/PEG. Dialysis membrane with higher ratio of acetic acid/PEG gives higher urea clearance percentage due to the formation of finger like macrovoids. The relation between the urea clearance and the ratio of acetic acid/PEG in the given range of 4 – 14, was a quadratic model and the mathematical model suggested could adequately describe the performance indicators within the limits mentioned

The Effects of Conceptual and Logical Interfaces On Visual Query Performance of End Users

To the end users, the interface is the system. A better interface not only facilitates end user interaction with the database, it also enables them to formulate queries more efficiently and effectively. Two of the most important user-database interfaces are the conceptual and logical interfaces. With the conceptual interface, the user communicates with the database system in terms of entities, objects and relationships. On the other hand, the current user-database interaction is mainly based on the logical interface where the user expresses the queries in terms of relations and join operations. Because the concepts at the logical interface are abstract and convoluted to ordinary users, many researchers argue that end users will be better off with the conceptual interface. This research will test this claim by comparing the effects of coneeptual and logical interfaces on the visual query performance of end users. The experimental study involves three tests: an initial test, a retention test and a relearning test. This allows us to assess the learning effect over time. The results show that users of the conceptual interface achieve higher accuracy, are more confident in their answers, and spend less time on the queries than users of the logical interface in all three tests

The effects of goal orientations on knowledge management system usage, knowledge sourcing and learning outcome

This research investigates individual differences in the context of knowledge management system (KMS) usage, knowledge sourcing and learning outcome. Individual differences are measured for mastery, performance and avoidance goal orientations. Individuals with high mastery goal orientations prefer to master and develop new skills and knowledge. Those with high performance goal orientations prefer to compare their performances with others. Lastly, those with high avoidance goal orientations prefer to avoid a new task if they feel incompetent. User posting and reading activities in a KMS are examined over a 3- month period. Consistent with goal orientation theory, the results show that mastery goal orientation has an effect on reading, knowledge sourcing and learning outcome. In contrast, performance goal orientation has an effect only on posting, but not on reading. To a lesser degree than mastery goal orientation, avoidance goal orientation has an effect on reading, but not posting. These findings have important implications for both knowledge management researchers and practitioners

Mining Of Resource Usage Using Evoc Algorithm In Grid Environment.

This paper addresses the new algorithm namely Evolving Clustering (Evoc A1goritbm) which is an improved version of Evolving Clustering Method (ECM). The algorithm bas been evaluated using three main criteria; that is dynamicity, accuracy and the ability to identify the stable cluster members

Psychometric properties of the smartphone addiction proneness scale in a sample of Malaysian adolescents

The aim of this study was to examine the psychometric properties of the 15-item smartphone addiction proneness scale (SAPS) among a sample of Malaysian adolescents. The gathered data were subjected to exploratory and confirmatory factor analysis. There were 922 secondary school students involved in this study. The exploratory factor analysis extracted a three-factor solution for SAPS. These factors were named disturbance of adaptive functions, withdrawal and tolerance. Results from confirmatory factor analysis also indicated that the three-factor structure fits well with the data. The internal consistency of the scale was found to be good. The positive and moderately strong correlation between SAPS and three widely adopted criterion variables (depression, loneliness and boredom proneness) supported the concurrent validity of SAPS. The results of this study showed that the SAPS is a reliable and valid instrument for identifying problematic smartphone use among Malaysian adolescents

Types of smartphone usage and problematic smartphone use among adolescents: A review of literature

This review aimed to provide an overview of the influence of social and process smartphone use on problematic smartphone use (PSU) among adolescents aged between 10-24 years old. Social smartphone use comprises three types of smartphone features: social networking sites, chatting/texting/instant messaging, and video/phone calls. On the other hand, categories of process smartphone use include watching videos/television/movies, web surfing, playing games, listening to music/podcasts/radio, and educational learning. There were 42 studies with a total of 139,389 adolescents met the criteria for inclusion after a thorough search of academic databases. Overall, the evidence from the studies included in this review revealed that chatting/texting, video/phone calls, watching videos/television/movies and music/podcasts/radio were positively and significantly linked to and predicted problematic smartphone use. Social networking sites use, instant messaging, gaming, web surfing and educational learning yielded inconsistent results. They could have a positive or negative relationship with PSU and play a role in predicting PSU. More research is needed for music/podcasts/radio and video/phone calls because the results are still scarce

Transient analysis and modelling of multimachine systems with power electronics controllers for real-time application

Electricity usage has grown steadily ever since the first commercial generator came into operation more than one century ago. Power transmission networks too, have grown in size and in operational complexity to be able to handle the large blocks of electricity that travel from generator to consumers round-the-clock and with huge variations. At various stages of the development, state-of-the-art equipment, methods and techniques have been incorporated in the vast array of tools that power systems engineers have at their disposal to keep up with the demands imposed by the planning, management, operation and control of modern power systems. Transient stability has always been an issue of paramount importance in power system planning and operation. Arguably, most of the ideas and concepts associated with power system stability analysis were conceived many years ago. Nonetheless, continuous expansion of the network and the emergence of a new generation of fast acting, multi-purpose power system controllers have called for renewed research efforts in this all-important application area of power systems. In particular, there is growing concern that the power network is becoming more unbalanced, owing to higher operating voltages and a relentless drive for interconnection, and that unbalances may impair the effectiveness of power electronic-based loads and controllers. These are issues that may be difficult to address satisfactorily with conventional transient stability modelling approaches since they are based on the premise that the transmission network observes a perfect balance, even under faulted operating regimes. The study of a limited range of asymmetrical transient stability problems using conventional methods can be achieved, but only with great difficulty, which involves transforming the network into fictitious components (i. e. symmetrical components). This is significant since asymmetrical short-circuit faults constitute the largest percentage of faults that occur in the power network, and network designs based solely on the three-phase short-circuit-to-ground faults result in underengineered networks. Equally important issues are the widespread commissioning of modern power electronics controllers and the lack of suitable models and methods for assessing the impact of such controllers in network-wide operation with particular reference to transient stability and unbalanced operation. The research reported in this thesis addresses these issues and develops a direct time phasedomain model for conducting multimachine transient stability analysis where asymmetrical operating conditions and the impact of modem power electronics controllers are represented. In this simulation environment, AC synchronous and asynchronous generators are represented together with asynchronous motors. The set of non-linear equations describing the machines are solved using discretisation and the trapezoidal rule of integration. The proposed model is compared against an industry standard power system package for cases of symmetrical operation. The generality and versatility of the model is demonstrated when applied to the analysis of symmetrical and asymmetrical power system operations. An important aspect of this research is a drive towards the solution of transient stability in real-time, where the results produced are in actual world time. This is achieved by embedding the model into a commercially available multi-purpose real-time station. To this end, coherency-based synchronous generators equivalent has been developed to enable the solution of multimachine systems in real-time. The equivalent unit is obtained based on the aggregation of the coherent generators using phase-domain techniques. Dynamic loads in the form of asynchronous motors are implemented within the multimachine network. The adverse influences of motor operation on voltage problems in the network under symmetrical and asymmetrical conditions are analysed. Transient analysis of dispersed generation is also considered where the asynchronous machine is operated as a generator alongside synchronous generators. The behaviours of the two type of generators under various networks and operating conditions are presented. Models of power electronics controllers in the direct time phase-domain are also described in this thesis. The generalised models of the Static Var Compensator (SVC), Static Synchronous Compensator (STATCOM), Dynamic Voltage Restorer (DVR) and High Voltage Direct Current-Voltage Source Converter (HVDC-VSC) station are proposed. The SVC comprised of a fix capacitor and a thyristor controlled reactor (TCR) is developed. Here, switching functions are used to represent the operation of the thyristor. Models of STATCOM, DVR and HVDC-VSC station are developed based on the self-commutated voltage source converter (VSC) technology. The VSC is represented by the switching functions of its pulse width modulation (PWM) control, hence, providing a flexible model within the direct time phase-domain approach. The model of the VSC is implemented into the respective power electronics controllers enabling a convenient modular approach to be adopted. The power electronics controllers are incorporated into the multimachine environment for the analysis of transient and power quality related issues