Urinary dysfunction in Duchenne muscular dystrophy

In Duchenne muscular dystrophy (DMD), sphincter muscles tend to be clinically spared. However, urinary incontinence is occasionally reported, usually late in the course of the disease. We wished to determine the etiology of urinary dysfunction in patients with DMD. Seven boys with DMD and urinary dysfunction were examined by a neurologist and a urologist followed by urodynamic and electrophysiological assessment. Based on the results of these evaluations, patients were defined as having an upper motor neuron (UMN), lower motor neuron (LMN), or myopathic lesion. Five of the patients had UMN abnormalities consisting of either uninhibited contractions or bladder/sphincter dyssynergy. One patient had a LMN lesion with prolonged duration and high-amplitude motor units. No patient demonstrated myopathic motor units. Five boys had undergone spinal fusion for scoliosis. We conclude that urinary incontinence in DMD is most often due to UMN dysfunction and not due to a severe myopathy of the detrusor or external sphincter. The most likely causes of the UMN abnormalities are severe scoliosis or a complication of spinal fusion surgery.     

Study of HVDC controls through efficient dynamic digital simulationof converters

The authors describe a converter model for 6/12 pulse operation and present its application to the study of the performance of converter controls. The simulation is simplified by considering a time-varying equivalent circuit on the DC side, which is derived on the basis of graph theory. Elimination of the need to store connection matrices and a fast and efficient way of generating the converter equations are further innovations introduced here. For the simulation of the HVDC (high-voltage direct-current) system the approach used is to model each component separately and in a modular fashion. These models are interconnected using appropriate interface variables. The control of converters based on digital techniques is considered along with voltage-dependent current order limit (VDCOL). Results for a two-terminal HVDC system under normal operation and abnormal conditions are presented to illustrate the capability of the simulation method     

Particle swarm optimization for determining shortest distance to voltage collapse

This paper describes an algorithm for computing shortest distance to voltage collapse or determination of CSNBP using PSO technique. A direction along CSNBP gives conservative results from voltage security view point. This information is useful to the operator to steer the system away from this point by taking corrective actions. The distance to a closest bifurcation is a minimum of the loadability given a slack bus or participation factors for increasing generation as the load increases. CSNBP determination has been formulated as an optimization problem to be used in PSO technique. PSO is a new evolutionary algorithm (EA) which is population based inspired by the social behavior of animals such as fish schooling and birds flocking. It can handle optimization problems with any complexity since mechanization is simple with few parameters to be tuned. The developed algorithm has been implemented on two standard test systems.     

Economic Dispatch Accounting Line Flow Constraints Using Functional Link Network

This paper presents a methodology for economic dispatch accounting line flow constraints in base case conditions. Functional Link Network (FLN) developed by Pao in 1989 has been used for this purpose. This single layer network has been trained using delta rule. Training set data have been obtained using Davidon-Fletcher-Powell's (DFP) method accounting inequality constraints by exterior penalty function method. An optimal brain damage technique has been employed for truncation and elimination of small weights. The algorithm is tested on IEEE 6-bus and 14-bus test systems.     

A Practical Model for Generator Maintenance Scheduling with Transmission Constraints

In this paper an optimal maintenance scheduling of generating units in a power system has been developed with transmission network representation. Here a DC load flow has been embedded in the maintenance model to include network constraints resulting in a more practical maintenance schedule. The model developed here uses the minimization of system cost (production cost plus the unserved energy cost) as the objective criterion, whereas the reliability objective function used is the minimization of unserved energy. The optimization is achieved by integer linear programming. The incorporation of transmission network adds significant complexity to maintenance scheduling. The proposed model enables almost all practical maintenance scheduling constraints to be handled easily. The optimization has been carried out to minimize the cost function considering different cases (i.e., with and without incorporation of the transmission network). The effectiveness of the proposed method has been demonstrated by obtaining numerical results on sample and real scale test systems. A comparison of the cost objective function clearly indicates that the maintenance schedule obtained from the simple generation model alone is more expensive than the one with transmission, and that there is a considerable degree of suboptimality in the former case.     

Sensitivity Analysis of the Ampacity,Cable and System Losses of 345 kV Pipe-Type Cable Systems

ABSTRACT

The affects of various parameters on the ampacity, cable and system looses of 345 kV oil-paper insulated naturally-cooled and forced cooled cable systems are considered and the sensitivity values are tabulated. The parameters which are of significance from the ampacity increase and energy conservation point of view are identified.     

A real-time ferroalloy model for the optimum ladle furnace treatment during the secondary steelmaking

Various means are applied in the steel making process to attain the desired chemistry. The final chemistry adjustments are made predominantly during the secondary metallurgy route in which ferroalloys (FAs) are added. With the availability of various FAs, it becomes necessary to identify the comparatively cheaper and optimum amount of FAs. The traditional practice of manually determining the quantity of FAs could not optimise the complete process. It is, therefore, necessary to determine the optimum FA addition without any human intervention. This paper presents a ferroalloy model in which a two-step incremental approach is adopted in ladle furnace (LF) to resemble the current operational practice. The model is designed such that no external intervention is needed to determine the required FA amount to be added. This results in low cost and high quality. The model after rigorous validation has been implemented in all three LFs in Tata Steel LD shop. This resulted in less FA consumption and achievement of the specified steel chemistry.     

A mathematical model to control thermal stability of blast furnace using proactive thermal indicator

The determination of thermal condition of the blast furnace is necessary for various reasons, such as to facilitate the operation, maintain a stable furnace condition, predict heat or heat tendency of the furnace and predict hot metal temperature (HMT). It can become a tool for controlling the product quality of the blast furnace. This paper presents a mathematical model for estimating the thermal tendency of the blast furnace. The thermal condition of the blast furnace is represented as thermal energy index, wherein a high thermal energy index denotes heating up of furnace, while a low thermal energy index indicates chilling down of furnace. Using this model, one could hypothetically estimate the thermal condition of the blast furnace in real time. Thereby, corrective controllable actions can be taken on real time to attain the desired HMT before the arrival of actual hot metal analysis.     

Magnetic properties of iron nanoparticles prepared by exploding wire technique

Nanoparticles of iron were prepared in distilled water using very thin iron wires and sheets, by the electro-exploding wire technique. Transmission electron microscopy reveals the size of the nanoparticles to be in the range 10 to 50 nm. However, particles of different sizes can be segregated by using ultrahigh centrifuge. X-ray diffraction studies confirm the presence of the cubic phase of iron. These iron nanoparticles were found to exhibit fluorescence in the visible region in contrast to the normal bulk material. The room temperature hysteresis measurements upto a field of 1.0 tesla were performed on a suspension of iron particles in the solution as well as in the powders obtained by filtration. The hysteresis loops indicate that the particles are superparamagnetic in nature. The saturation magnetizations was approximately 60 emu/gm. As these iron particles are very sensitive to oxygen a coating of non-magnetic iron oxide tends to form around the particles giving it a core-shell structure. The core particle size is estimated theoretically from the magnetization measurements. Suspensions of iron nanoparticles in water have been proposed to be used as an effective decontaminant for ground water.     

Efficient Multiscale Modeling Framework for Triaxially Braided Composites using Generalized Method of Cells

In this paper, a framework for a three-scale analysis, beginning at the constituent response and propagating to the braid repeating unit cell (RUC) level, is presented. At each scale in the analysis, the response of the appropriate RUC is represented by homogenized effective properties determined from the generalized method of cells micromechanics theory. Two different macroscale RUC architectures are considered, one for eventual finite-element implementation and the other for material design, and their differences are compared. Model validation is presented through comparison to both experimental data and detailed finite-element simulations. Results show good correlation within range of experimental scatter and the finite-element simulation. Results are also presented for parametric studies varying both the overall fiber volume fraction and braid angle. These studies are compared to predictions from classical lamination theory for reference. Finally, the multiscale analysis framework is used to predict the onset of failure in a transversely loaded triaxially braided composite. The predicted transverse failure initiation stress value shows excellent correlation and provides the bound for which linear elastic constitutive models are acceptable for implementation.