Load Relief Research Articles

Load relief device of the neck cooling belt for persons with spinal cord injury

Load relief device of the neck cooling belt for persons with spinal cord injury

Grid capacity released analysis and incremental addition computation for distribution system planning

This paper presents a released capacity analysis for the power delivery system of the distribution grid, and the computation of the incremental capacity addition provided by an optimally deployed photovoltaic (PV) system in the IEEE 13 and 34 test feeders. The intrinsic strong correlation that exists between network capacity and reliability gives the inclusion of renewable distribution generation (DG) and the evaluation of their additional load serving capacity a prime place in the emerging active distribution system planning (ADSP). Also, this article presents a method capable of measuring risk and upgrade deferral in the evolving ADSP using two energy quantities referred to as the energy exceeding normal (EEN) and unserved energy (UE). The evaluation of these metrics is used to assess system capacity usage, and as a planning tool to identify required system upgrade and measure the effectiveness of the applied DG incremental solution. This analysis is pivotal as the load growth continues to outpace new feeder construction and network expansion becomes difficult and costly. Therefore, utilizing DG to provide peak load relief and incremental capacity solution is developing into a viable alternative. In addition, results presented in this article show that apart from optimal positioning and sizing, maximizing the value attributes of PV-DG also, depends on its ability to produce power at proper times and levels. Also, since energy is the quantity being sold, this article further presents a simple economic analysis based on EEN and loss savings which can be used to compare alternative power generation sources.

Load relief control of launch vehicle using aerodynamic angle estimation

A nonlinear closed-loop load relief scheme is proposed to reduce the aerodynamic load during the ascent phase of a launch vehicle. The proposed controller is designed based on a back-stepping and sliding-mode control scheme with aerodynamic angle feedback. A hybrid load-relief strategy using the load relief scheme around the period of the maximum dynamic pressure and the traditional minimum-drift scheme during the other period is proposed. An aerodynamic angle estimator is also developed using a Kalman filter for the feedback of the load relief control. Numerical simulation is conducted to demonstrate the performance of the proposed strategy as well as the potential benefits.

Creep of Steam-Turbine Diaphragm Under Variable Loading Conditions

The authors put forward a procedure of creep analysis for variable loading conditions, which involves the use of the incremental creep theory and finite element method. Variable loading with load increase and relief at a constant temperature is considered as a stepwise process. The authors study a growth of deflections and stress relaxation in a intermediate-cylinder diaphragm of a steam turbine in various loading modes as well as special features of residual stress distribution in fixed blades.

Reducing Induced Drag and Maneuver Loads by Active Aeroelastic Alteration

Induced-drag reduction and maneuver load relief are two recent benefits of active aeroelastic wing technology. Judiciously deflecting wing-edge flaps can alter an unfavorable force distribution aeroelastically. Active distribution matching control to reduce induced drag and active load alleviation control by reducing wing bending moments are such active aeroelastic wing applications. Kolonay and Eastep (“Optimal Scheduling of Control Surfaces on Flexible Wings to Reduce Induced Drag,” Journal of Aircraft, Vol. 43, No. 6, Nov.–Dec. 2006, pp. 1655–1661) posed a least-squares problem to match the calculated distribution to an elliptic distribution. Zink et al. (“Maneuver Trim Optimization Techniques for Active Aeroelastic Wings,” Journal of Aircraft, Vol. 38, No. 6, 2001, pp. 1139–1146) posed aircraft trimming as bending-moment minimization to provide external-load relief at the wing root. Analytic gradients, exact aeroelastic analyses, and closed-form trim solutions are unique features of the Automated Structural Optimization System. Both teams employed the Automated Structural Optimization System to solve their multidisciplinary optimization problems but still encountered inconveniences in obtaining required sensitivity data and in performing required trim optimization. This paper treats two forms of active aeroelastic alteration, with each being a generalization of these active distribution matching control and active load alleviation control formulations, and it develops analytic solution techniques that render the sensitivity evaluations and optimization calculations natural and convenient. Two strategies combine to resolve the inconveniences and enable in-process noniterative trim optimization and analytic sensitivity evaluation. The active aeroelastic alteration solution techniques are demonstrated by results of initial test and verification on a classical forward-swept wing example.

From syntagmatic to paradigmatic spatial zeroes: The loss of the prepositionsein inner Asia Minor Greek

AbstractWe trace the diachronic development of the prepositionsein inner Asia Minor Greek from its use to mark a range of spatial functions to its ultimate loss and replacement by zero. We propose that, before spreading to all syntactic and semantic contexts, zero-marking was contextually-dependent on the presence/absence of a prenominal genitive modifying the head noun of Ground-encoding NPs and on the presence/absence of Region-encoding postpositions. We attribute these developments to an informational load relief strategy aimed at producing more economical utterances, as well as to language contact with Turkish, which favored structural convergence on the adpositional level between the two languages.

Active disturbance rejection control method on load relief system for launch vehicles

Active disturbance rejection control method on load relief system for launch vehicles

Development of Lower Back Bending Load Relief Mechanism using Principle of Leverage for Lifting a Heavy Object by Hand

In the present paper, a lower back bending load relief mechanism using a principle of leverage for lifting a heavy object by hands was proposed and the function was evaluated. In the broad range of such as care, logistic and agriculture fields, there are many tasks required being bending the lower back for lifting a heavy object, and it has been a cause of lower back pains. Since the developed device is touched to three body points - (1) chest, (2) lower back and (3) thighs, the heavy object load firstly would get on the chest part, and the rotational movement to fall down forward would be cancelled by the thighs and the lower back parts. 100 N load lifting experiment when 30, 45, 70° with the proposed device shows that the calculated rotational torque of the lower back takes a small value (at least <2 Nm), in the case of without the proposed device, the rotational torque would take about 49 Nm. The mechanism would be useful to relive the lower back rotational load when the subject holds a heavy load by the hands.

Achieving load relief with minimal change in conventional control law of a launch vehicle

Abstract This article is about managing the structural load due to winds on a launch vehicle during its atmospheric flight. Wind generates aerodynamic force on the vehicle. The other sources of force on the vehicle are thrust and weight. These forces generate moment on different structural members of a launch vehicle, depending on their point of application with respect to the location of a particular structural member. Together these forces and moments generate tension, compression, shear and bending loads at different locations on the launch vehicle. If the in-flight loading exceeds the structural limit of any member, the vehicle would break. In this paper we have explored the possibility of achieving load relief without using any additional sensor or scheduling of any additional gain. This methodology is useful if the requirement for achieving load relief comes very near to the launch date. In this scenario, the control designer will not have enough freedom to go for wholesale changes in the already existing onboard software of a prevailing conventional control law. This restriction is due to the necessary time required for verification and validation of modifications in code.

Optimal Load Shedding Strategy for Selçuk University Power System with Distributed Generation

Traditionally under frequency relays and PLCs (programmable logic controller) are used for load shedding. Recently, these methods have been combined with smart power management systems to shed load automatically. These combined systems are the best methods. However, shedding exact amount of load is almost impossible, because it usually ends up with excessive or inadequate load shedding at feeders where it becomes necessary to sustain system stability. Disconnecting a certain amount of loads at a feeder is defined as load shedding. In case of emergency, faster and optimal load relief can be obtained with an intelligent load shedding system. This paper demonstrates an intelligent load shedding strategy in electrical system of Selçuk University Medical Faculty consisting different type and size of loads and being supplied by a distributed generator. Generators which supply with Selçuk University Medical Faculty can’t meet energy requirement when there is a disturbance in power system. In case of 1 MW Solar power plant to be building at University Campus supply to Medical Faculty, the difference between power generation and demand will decrease. In this case, load shedding becomes necessary to improve reliability of power supply and sustain system stability. Loads are sorted by importance priority and optimal load shedding method is applied. The fuzzy logic is employed for optimal load shedding solution. Strategy is applied on Medical Faculty loads which have different importance level.

Automatic load relief numerical predictor-corrector guidance for low L/D vehicles return from low Earth orbit

The poor maneuverability of low lift-to-drag ratio (L/D) vehicles results in low precision of reference-trajectory guidance and difficulty in meeting load constraints. This paper presents an automatic load relief numerical predictor-corrector method for the guidance of low L/D vehicles return from low Erath orbit. By elaborately designing a bank-angle profile in each guidance circle and selecting appropriate iteration parameters, the goal of automatic load relief is achieved, which greatly reduces the maximum peak load. With the use of coupled guidance and landing error feedback algorithms, the guidance precision is improved. Aerodynamic coefficients of the vehicle and landing errors are filtered to further increase the robustness of the algorithm. Extensive Monte Carlo simulations are conducted to evaluate and verify the design features of the algorithm. The test results show that the algorithm consistently offers very satisfactory performance even in highly dispersed cases. Such an algorithm holds distinct potential for onboard applications.

Graphical and Analytical Methods for Stalling Analysis of Engine Generator Sets

Reciprocating engine driven generator sets (or “gensets”) are a leading class of distributed energy resources (DERs) from the low kilowatt up to hundreds of kilowatt ratings. Natural-gas-based DERs are more likely to be favored by both industries and utilities in the near future because of their low cost due to the newly found shale deposits at many places in the world. The DERs such as gensets when operating under islanded conditions are susceptible to stalling and can bring down the entire industrial power system, particularly if they are loaded beyond 80% of the rated engine capacity. This paper presents graphical and analytical methods to determine the stalling conditions of the most common type of gensets that have a synchronous generator as the utility interface. A systematic approach is developed from the first principles of generator electromagnetic energy conversion. The engine fuel map limits have been integrated into the generator speed versus active power characteristics for this purpose. The stalling prevention by applying an underfrequency load relief (V/Hz) scheme is also discussed.

Sensitivity analysis of demand-side management impact on Abu-Dhabi’s electricity consumption

The difficulty to accurately assess the impact of energy efficiency retrofits and the impact of energy efficiency policies is a widely recognized barrier to the wider deployment of Demand-Side Management (DSM). The task is complicated by the dynamic nature and coupled interaction of the sub-system and the high correlation with weather and other perturbations. A regression-based model of the load is estimated using measured data from the pre-DSM period for the city of Abu Dhabi, UAE, and is then used to generate proxies representing the main characteristics of the Abu Dhabi urban buildings which impact the cooling load. The sensitivity analysis to variations of the most important proxies that drive cooling load was performed, and the impact assessed for the aggregate urban area of Abu Dhabi municipality. Well targeted DSM interventions can achieve an average 20% improvement of the cooling process in Abu-Dhabi. The present study estimates that an emirate-wide program could result in a peak load relief of 6.6% and annual energy conservation of 9.2% (respectively 450 MW and 3,600 GWh based on 2010 emirate-wide electricity use statistics).

Analysis and relief method of reentry aerodynamic load based on matched asymptotic expansions method

Reentry velocity of lunar module reaches the second cosmic velocity, which could make the aerodynamic environment insupportable. So it is essential to analysis the reentry aerodynamic load. The equation of motion for reentry vehicle is a group of ordinary differential equations, and numerical methods are inadequate for online mission because their computation amount is too large. An analytical method of solving the reentry equation of motion is proposed in this paper to analyze the reentry aerodynamic load. First, matched asymptotic method is used to obtain solutions of longitudinal equation of motion in outer and inner region independently and combine them to obtain a unified closed-form solution. Reentry aerodynamic load has been analyzed in three fragments using the closed-form solution, and approximate solution of load is compared with the exact solution. Second, suppositional initial conditions are obtained by solving the closed-form solution using current state, then an analytical method of predicting the first load peak is proposed, and the relative prediction error is analyzed for different bank angles. Third, the load relief method based on load peak prediction is proposed, which can redistribute the total dissipated energy in the whole reentry process, and the validity of the method is verified by Monte Carlo simulation.

PEDAGOGICAL RESEARCHES CONDUCTED AT UNIVERSITÉ DE SHERBROOKE

The USherbrooke Faculty of Engineering is recognized as a leader in innovation and research in engineering education. The Université de Sherbrooke was the second university in Canada to offer co-op programs for its students in 1966 and is now among the top 10 higher education institutions in North America for the significance of its co-op system. The faculty of engineering was the first in Canada to offer an undergraduate mechanical engineering program based on professional competencies with design as the ultimate competency integration activity - the backbone of the entire program. In 2001, we introduced completely redesigned electrical and computer engineering programs based on two complementary frameworks. The first one is a competency-based framework used to have a better alignment between teaching/learning activities, program objectives and competences development. The second one, called the learning framework, introduces a paradigm shift from passive to active learning methodologies with the deployment of problem and project based learning situations. Over the years, the faculty of engineering has developed many original approaches to both design of curriculum and faculty organisation. We also developed considerable expertise to improve teaching and learning especially integration of curriculum elements, the development of team skills and of a professional culture, the use of design projects extending over more than one year with links to industry, the use of portfolio to track competencies development, active learning environment such as problem and project-based learning and in utilising novel assessment techniques to improve learning. All these initiatives have been made possible by creating winning conditions to involve faculty members in pedagogical research activities and implementation methodologies. To do that we provided institutional financial support (faculty, university), encouragement, teaching load relief, recognition of faculty involvement in tenure and promotion, professional support for CEAB accreditation requirements, etc.

Coordinated agent-based control for online voltage instability prevention

In this paper, a new method for online voltage instability control suitable for smart grid application is proposed. The method uses the Maximum Loadability Index to determine the amount of load relief necessary to restore stability. This measure can be determined based on local measurements. The load relief is obtained by: increase of local generation, virtual load shedding via adjusting the Load Tap Changers (LTCs) set-point, intelligent load control and the increase of reactive power compensation from Static Var Compensators. For the local generation, the control of two types is described: for micro Combined Heat and Power (micro-CHP) units and for large synchronous generators. In order to obtain constant power supply from a group of micro-CHPs, a Virtual Power Plant coordination method is proposed. The control of the actuators is outlined, and a method is described to coordinate their actions. Based on simulations it is demonstrated that the proposed method works properly: voltage collapse can be avoided, and voltage stability is restored. A sensitivity analysis is performed to determine the optimal settings of the coordinated controller. Furthermore, the merit of including reactive power control in the proposed control strategy is investigated. Compared to classical controls, such as Under-Voltage Load Shedding and LTCs tap blocking, the method performs better. Copyright © 2013 John Wiley & Sons, Ltd.

Development of Emergency Department Load Relief Area—Gauging Benefits in Empirical Terms

The primary goal of this investigation was to develop a simulation model to evaluate the various internal and external factors affecting patient flow and crowding in the emergency department (ED). In addition, a few recommendations are proposed to reconfigure the patient flow to improve ED capacity while maintaining service quality. In this research, we present a simulation study conducted in the ED at the "S Hospital" located in Seoul. Based on patient flow data and process analysis, a simulation model of patient throughput in the ED has been developed. We evaluated simulations of diverting the specific patient load in the light of our proposed recommendations to a separately managed area named as the ED load relief area (ED-LRA) and analyzing potential effects on overall length of stay (LOS) and waiting time (WT). What-if analyses have been proposed to identify key issues and investigate the improvements as per our proposed recommendations. The simulation results suggest that specific patient load diversion is needed to ensure desired outcomes. With the diversion of specific patient load to ED-LRA, there is a reduction of 40.60% in mean LOS and 42.5% in WT with improved resource utilization. As a result, opening of an ED-LRA is justified. Real-world systems are often too intricate for analytical models and often too expensive to trial with directly. Simulation models allow the modeling of this intricacy and enable experimentation to make inferences about how the actual system might perform. Our simulation study modeled that diverting the specific patient load to ED-LRA produced an improvement in overall ED's LOS and WT.

Potential Inadequacy of Automatic Tube Compensation to Decrease Inspiratory Work Load After at Least 48 Hours of Endotracheal Tube Use in the Clinical Setting

Endotracheal tubes (ETTs) impose a substantial respiratory work load on mechanically ventilated patients. Automatic tube compensation (ATC) should overcome this flow-dependent resistive work load; however, ETT resistance can be increased by tracheal secretions or ETT deformities. Our bench study investigated whether ATC provides effective respiratory work load relief in used ETTs. We enrolled 20 critically ill patients requiring mechanical ventilation for longer than 48 hours. After extubation, we collected the used ETTs and measured the pressure-time products (PTPs) by using a bellows-in-a-box lung model that simulated spontaneous breathing, at a respiratory rate of 10 breaths/min, inspiratory time of 1.0 s, and tidal volumes (V(T)) of 300 mL, 500 mL, and 700 mL. The ventilator was set at ATC 100% with PEEP of 5 cm H(2)O and F(IO(2)) of 0.21. The flow and airway pressure at the proximal (P(aw)) and distal (P(tr)) ends of the ETT were recorded, and the PTP integrated from P(tr) analyzed. PTP values increased with V(T) during ATC. Even at 100% ATC the ventilator did not completely compensate for the PTP imposed by the ETT. In used ETTs, peak flow and peak P(aw) were lower and PTP values were greater than in new ETTs. As V(T) increased, the percentage difference in the PTP values between the new and used ETTs increased. ATC does not necessarily compensate for an ETT-imposed respiratory work load. ETT configuration changes and tracheal secretions can increase ETT resistance and decrease the ability of ATC to compensate for the increased respiratory work load.

Alterations in intermediate filaments expression in disc cells from the rat temporomandibular joint following exposure to continuous compressive force

The articular disc in the temporomandibular joint (TMJ) that serves in load relief and stabilizing in jaw movements is a dense collagenous tissue consisting of extracellular matrices and disc cells. The various morphological configurations of the disc cells have given us diverse names, such as fibroblasts, chondrocyte-like cells and fibrochondrocytes; however, the characteristics of these cells have remained to be elucidated in detail. The disc cells have been reported to exhibit heterogeneous immunoreaction patterns for intermediate filaments including glial fibrillary acidic protein (GFAP), nestin and vimentin in the adult rat TMJ. Because these intermediate filaments accumulate in the disc cells as tooth eruption proceeds during postnatal development, it might be surmised that the expression of these intermediate filaments in the disc cells closely relates to mechanical stress. The present study was therefore undertaken to examine the effect of a continuous compressive force on the immunoexpression of these intermediate filaments and an additional intermediate filament - muscle-specific desmin - in the disc cells of the TMJ disc using a rat experimental model. The rats wore an appliance that exerts a continuous compressive load on the TMJ. The experimental period with the appliance was 5 days as determined by previous studies, after which some experimental animals were allowed to survive another 5 days after removal of the appliance. Histological observations demonstrated that the compressive force provoked a remarkable acellular region and a decrease in the thickness of the condylar cartilage of the mandible, and a sparse collagen fiber distribution in the articular disc. The articular disc showed a significant increase in the number of desmin-positive cells as compared with the controls. In contrast, immunopositive cells for GFAP, nestin and vimentin remained unchanged in number as well as intensity. At 5 days after removal of the appliance, both the disc and cartilage exhibited immunohistological and histological features in a recovery process. These findings indicate that the mature articular cells are capable of producing desmin instead of the other intermediate filaments against mechanical stress. The desmin-positive disc cells lacked α-smooth muscle actin (α-SMA) in this study, even though desmin usually co-exists with α-SMA in the vascular smooth muscle cells or pericytes. Because the precursor of a pericyte has such an immunoexpression pattern during angiogenesis, there is a further possibility that the formation of new vessels commenced in response to the extraordinary compressive force.

TCP/IP Based Intelligent Load Management System in Micro-Grids Network Using MATLAB/Simulink

Computerized power management system with fast and optimal communication network overcomes all major dicrepencies of undue or inadequate load relief that were present in old conventional systems. This paper presents the basic perception and methodology of modern and true intelligent load management scheme in micro grids topology by employing TCP/IP protocol for fast and intelligent switching. The network understudy performs load management and power distribution intelligently in a unified network. Generated power is efficiently distributed among local loads through fast communication system of server in the form of source and clients in the form of loads through TCP/IP. The efficient use of information between server and clients enables to astutely control the load management in a power system of micro grids system. The processing time of above stated system comes out to be 10ms faster than others which ensure very less delay as compared to conventional methods. The Micro Grids system operating through TCP/IP control has been implemented in MATLAB/Simulink and results have been verified.