Load Adjustment Research Articles

Effect of gasified biomass fuel on load characteristics of an intermediate-temperature solid oxide fuel cell and gas turbine hybrid system

This work uses the mathematical model of an intermediate-temperature solid oxide fuel cell and gas turbine (IT-SOFC/GT) hybrid system to study the effects of gasified biomass fuels on system load characteristics. The system performance is investigated by using four types of fuels in each adjusting mode. The relation between the fuel type and load adjusting mode is obtained for users and designers to select the appropriate fuel for reasonable operation modes. Results show that the hybrid system of 182.4 kW has a high electric efficiency of 60.78% by using wood chip gas (WCG). If cotton wood gas (CWG) and corn stalk gas (CSG) are used, both boundary values of steam to carbon ratio (S/Cbv) and system power are higher, but system efficiencies decrease to 57.36% and 57.87% respectively. In the designed three load adjusting modes, the system can reach maximum efficiency over 59% with four types of biomass gases. If high efficiency and a wide range of load adjustment are required, users can select Case B to use fuels like WCG and GSG. When higher efficiency and low load is expected, Case A is more desirable. With fuels like CWG and CSG, the system has good safety performance in Case C.

The predictive value of the antioxidative function of HDL for cardiovascular disease and graft failure in renal transplant recipients

BackgroundProtection of low-density lipoproteins (LDL) against oxidative modification is a key anti-atherosclerotic property of high-density lipoproteins (HDL). This study evaluated the predictive value of the HDL antioxidative function for cardiovascular mortality, all-cause mortality and chronic graft failure in renal transplant recipients (RTR). MethodsThe capacity of HDL to inhibit native LDL oxidation was determined in vitro in a prospective cohort of renal transplant recipients (RTR, n = 495, median follow-up 7.0 years). ResultsThe HDL antioxidative functionality was significantly higher in patients experiencing graft failure (57.4 ± 9.7%) than in those without (54.2 ± 11.3%; P = 0.039), while there were no differences for cardiovascular and all-cause mortality. Specifically glomerular filtration rate (P = 0.001) and C-reactive protein levels (P = 0.006) associated independently with antioxidative functionality in multivariate linear regression analyses. Cox regression analysis demonstrated a significant relationship between antioxidative functionality of HDL and graft failure in age-adjusted analyses, but significance was lost following adjustment for baseline kidney function and inflammatory load. No significant association was found between HDL antioxidative functionality and cardiovascular and all-cause mortality. ConclusionThis study demonstrates that the antioxidative function of HDL (i) does not predict cardiovascular or all-cause mortality in RTR, but (ii) conceivably contributes to the development of graft failure, however, not independent of baseline kidney function and inflammatory load.

Demand Response With Capacity Constrained Supply Function Bidding

We study the problem faced by an operator who aims to allocate a certain amount of load adjustment (either load reduction or increment) to multiple consumers so as to minimize the aggregate consumer disutility. We propose and analyze a simple uniform-price market mechanism where every consumer submits a single bid to choose a supply function from a group of parameterized ones. These parameterized supply functions are designed to ensure that every consumer's load adjustment is within an exogenous capacity limit that is determined by the current power system operating condition. We show that the proposed mechanism yields bounded efficiency loss at a Nash equilibrium. In particular, the proposed mechanism is shown to achieve approximate social optimality at a Nash equilibrium, if the total capacity limit excluding the consumer with the largest one is much larger than the total amount of load to be adjusted. We complement our analysis through numerical case studies.

Determination of safe operation zone for an intermediate-temperature solid oxide fuel cell and gas turbine hybrid system

This paper proposes a novel approach to determine the safe zone for an intermediate-temperature solid oxide fuel cell and gas turbine hybrid system. The approach first ensures the compressor safety and then determines the overall system safe zone by analyzing the unsafe characteristics of main components. Safe performance of the hybrid system fueled with biomass gas at all operations is analyzed. Finally, the map of safe zone is obtained to avoid component malfunctions and system performance deterioration. Results show that the hybrid system can achieve a high efficiency 60.78%, which is an interesting reference for distributed power stations. Under all operations, two unbalanced energy zones exist, which may cause the short supply of O2 or fuel for electrochemical reaction. The lower the rotational speed of gas turbine, the narrower the zone of carbon deposition takes place in the reformer or turbine inoperation caused by too low inlet temperature. However, the phenomenon of fuel cell thermal cracking due to over-temperature will be exacerbated. System layout also affects component safety especially for the fuel cell. In the safe zone, the system has a characteristic of high efficiency and low load with low rotational speed, vice versa. In other words, the powers and load adjustment ranges both decrease with decreasing rotational speed whereas the efficiency increases, which peaks at 63.43%.

TSC-based Method to Enhance Asset Utilization of Interconnected Distribution Systems

This paper proposes a new planning method for interconnected smart distribution networks based on total supply capability (TSC), which provides better utilization of existing assets. The specific five steps of the proposed TSC-based planning are: 1) analysis of the power supply problem; 2) calculation of the TSC value; 3) verification and adjustment of TSC and total load; 4) verification between distributed TSC and each feeder load; and 5) ${N-1}$ simulation. The load allocation problem is solved with a model that is capable of searching optimized load allocation considering ${N-1}$ security constraints. Two planning cases are presented to illustrate this method and to compare it with traditional substation-network two-step planning. It is shown that the TSC-based planning can exploit existing networks efficiently and save money. The proposed planning approach is suitable for urban smart distribution networks featured by distribution automation and large-scale interconnection.

EFEITO DO TREINAMENTO MUSCULAR INSPIRATÓRIO ASSOCIADO A REABILITAÇÃO FÍSICA APÓS HOSPITALIZAÇÃO PROLONGADA: SÉRIE DE CASOS

Introdução: A sarcopenia, a polineuropatia do paciente crítico e fraqueza muscular respiratória são algumas das possíveis condições responsáveis por essa incapacidade física após a hospitalização prolongada. Objetivo: Relatar o efeito do treinamento muscular inspiratório e programa de exercícios físicos na capacidade muscular respiratória e funcional de uma série de casos de pacientes pós-hospitalização. Métodos: Série de casos, do uso do TMI e reabilitação física domiciliar em pacientes em deshospitalização. O protocolo respiratório empregou carga aproximada de 50% da pressão inspiratória máxima (Pimax), realizado em duas séries de 30 repetições por dia durante sete dias por semana. As variáveis mensuradas antes e após as intervenções foram Pimax, Capacidade Vital (CV) PFI (Pico de fluxo inspiratório), força muscular periférica (MRC) e independência funcional (índice de Barthel completo e domínio mobilidade da Medida de Independência Funcional (MIF). Resultados: A amostra foi composta por dez pacientes com idade média 73,7±13,6 anos e tempo de internação hospitalar 18,6±10,9 dias, sendo que a adesão as intervenções foi de 82,0%. Nas 459 sessões de TMI houveram 25 eventos adversos ocorridos durante os ajustes de carga, porém sem necessidade de exclusão após retorno a carga inspiratória prévia. Após quatro semanas das intervenções, observou-se aumento significativo da Pimax, PFI e CV, além de ganhos na força muscular periférica e capacidade funcional. Conclusão: O TMI associado a reabilitação física em pacientes críticos após hospitalização promoveu ganhos na função respiratória e capacidade funcional após quatro semanas de intervenção.

An Efficient Decomposition Method for the Integrated Dispatch of Generation and Load

In response to the computational challenges produced by the integrated dispatch of generation and load (IDGL), this paper proposes a novel and efficient decomposition method. The IDGL is formulated using the mixed-integer quadratic constrained programming (MIQCP) method. To efficiently solve this complex optimization problem, the nodal equivalent load shifting bidding curve (NELSBC) is proposed to represent the aggregated response characteristics of customers at a node. The IDGL is subsequently decomposed into a two-level optimization problem. At the upper level, grid operators optimize load shifting schedules based on the NELSBC of each node. Transmission losses are explicitly incorporated into the model to coordinate them with generating costs and load shifting costs. At the bottom level, customer load adjustments are optimized at individual nodes given the nodal load shifting requirement imposed by the grid operators. The key advantage of the proposed method is that the load shifting among different nodes can be coordinated via NELSBCs without iterations. The proposed decomposition method significantly improves the efficiency of the IDGL. Parallel computing techniques are utilized to accelerate the computations. Using numerical studies of IEEE 30-bus, 118-bus, and practically sized 300-bus systems, this study demonstrates that accurate and efficient IDGL scheduling results, which consider the nonlinear impact of transmission losses, can be achieved.

Personalized Adaptive Control of Training Load in Cardio-Exergames--A Feasibility Study.

This article presents a feasibility study of using an algorithm for an individual and adaptive control of training load in an ergometer-controlled exergame for aerobic training. An additional goal was to investigate the effects of the adaptive game on the players' motivation. A two-phase approach (calibration and exercise phase) was applied in a sample of 16 physically active adults. In the cardio-exergame "LetterBird," the flight of a pigeon was controlled by the pedaling rate of a bike ergometer as input device. During the calibration phase the individual heart rate (HR) responses of the players were measured. In the exercise phase, these data were used to adjust the resistance of the ergometer using the proposed algorithm. The purpose of this algorithm was to induce an individually defined target HR and to keep it in a steady state. In order to establish a reference for further studies, the game experience was measured using the kids-Game Experience Questionnaire. In 15 of 16 participants the actual HR reached the intended individual HR range within 10 minutes after onset of exercise. However, the induced HR initially exceeded the target HR in 13 participants, which made load adjustments necessary. The analysis of the kids-Game Experience Questionnaire confirmed the motivational effect of the exergame "LetterBird." The results confirm that the proposed algorithm for personalized HR control in the game "LetterBird" is feasible. Furthermore, the cardio-exergame "LetterBird" seems to have a substantial short-term motivating effect.

Leaf carbohydrate metabolism in Malbec grapevines: combined effects of regulated deficit irrigation and crop load

Background and Aims Regulated deficit irrigation and crop load adjustment are viticultural practices used to improve grape and wine composition. Our objective was to evaluate the combined effect of irrigation and crop load levels on leaf photosynthesis, accumulation of non-structural carbohydrates and leaf carbon utilisation during the season. Methods and Results The trial started in 2006 in a Vitis vinifera L. Malbec vineyard in Mendoza. Two irrigation levels (100% and 25% of reference evapotranspiration) and two crop loads (20 and 10 bunches per vine, set at veraison) were studied. During the 2009/10 season, diurnal dynamics of leaf water potential, photosynthesis and carbohydrate concentration were determined at anthesis, veraison and harvest. Deficit irrigation reduced leaf starch concentration at veraison and increased soluble sugars. High-crop load reduced leaf starch concentration at veraison. Starch turnover was correlated with photosynthesis during the previous day. Conclusions Deficit irrigation had a greater effect on carbon allocation between soluble sugars and starch than on total carbohydrate production. Effects of deficit irrigation and crop load operated independently. Significance of the Study This experiment improved our knowledge of carbon assimilation and allocation during the season, which may assist the development of management practices to stabilise yield and fruit composition.

Soluble CD14: An Independent Biomarker for the Risk of Mother-to-Child Transmission of HIV in a Setting of Preexposure and Postexposure Antiretroviral Prophylaxis.

Elevated soluble CD14 (sCD14) concentrations, a marker of monocyte activation, predicts adverse outcomes in human immunodeficiency virus (HIV)-infected adults. To examine the association of sCD14 concentrations with the risk of mother-to-child transmission (MTCT) of HIV, we nested a case-control study (49 pairs of infants and their HIV-infected mothers) within the Six-Week Extended-Dose Nevirapine trial. Median peripartum maternal log2 sCD14 concentration was higher among transmitters (defined as pairs in which maternally transmitted HIV infection occurred by 12 months of age) than nontransmitters (20.29 pg/mL vs 19.41 pg/mL; P = .005). There was an increased odds of MTCT for every log2 increase in maternal sCD14 concentration, after adjustment for maternal HIV load, CD4 count and cART exposure (adjusted odds ratio, 3.51; 95% confidence interval, 1.21-10.21). Maternal monocyte activation may adversely influence the risk of MTCT of HIV.

Mechanical blossom thinning of apples and influence on yield, fruit quality and spur leaf area

McClure, K. A. and Cline, J. A. 2015. Mechanical blossom thinning of apples and influence on yield, fruit quality and spur leaf area. Can. J. Plant Sci. 95: 887–896. Apple (Malus×domestica Borkh.) trees tend to crop heavily, which often makes crop load adjustment necessary. This can now be achieved as early as bloom by mechanical removal/thinning of blossoms. High-density Empire/M.26 and Royal Gala/M.26 apple trees were mechanically (MBT) and hand blossom thinned (HBT) in 2010 and 2011, respectively, and their effects on fruit set, subsequent hand thinning, final crop load, and spur leaf area were measured. In both years, MBT effectively thinned trees and reduced fruit set, but did not reduce the requirement for follow-up hand fruitlet thinning after June drop in 2011. In 2010, harvest yields for MBT treatments decreased, while weight and diameter increased. In 2011, most harvest and fruit quality parameters were unaffected by thinning. Trees that were mechanically thinned had significantly reduced spur leaf area, but were similar to unthinned control trees with respect to many of the yield and quality parameters measured. Mechanical blossom thinning is a new crop load management option for apple growers looking to supplement more traditional chemical and hand thinning techniques.

Effect of operating parameters on a hybrid system of intermediate-temperature solid oxide fuel cell and gas turbine

In this work, detailed mathematical models of a hybrid system of an IT-SOFC (intermediate-temperature solid oxide fuel cell) and a GT (gas turbine) that is fueled by gasified biomass gas are built. Under the constraints of the working temperature of the fuel cell, mean axial temperature gradient, compressor surge, and turbine inlet temperature, the effects of operating parameters on the hybrid system are investigated mainly including RS (rotational speed), F/A (fuel/air) ratio, and S/C (steam/carbon) ratio. The electrical efficiency is 59.24% under the design condition. The power and efficiency of the system both decrease as the RS increases, with the latter decreasing from 60.95% to 49.08%. If the RS is too low, the system operation goes beyond the safety zone. In this situation, both the fuel cell and the turbine may be subjected to excess temperatures, and the compressor may easily surge. The efficiency increases from 56.5% to 61.34% with increasing F/A ratio, but an extremely high F/A ratio can cause the turbine to suffer from excess temperature. The efficiency decreases from 61.12% to 56.8% with increasing S/C ratio. The following two conclusions are drawn. First, the F/A ratio has the greatest influence on the performance of the hybrid system, i.e., its adjustment can effectively change the load in a wide range. Second, the RS and S/C ratio are suitable for load adjustment in a narrow range.

Study of regeneration system of 300 MW power unit based on nondeaerating heat balance diagram at reduced load

More than 30 power units of thermal power stations, based on the nondeaerating heat balance diagram, successfully operate in the former Soviet Union. Most of them are power units with a power of 300 MW, equipped with HTGZ and LMZ turbines. They operate according to a variable electric load curve characterized by deep reductions when undergoing night minimums. Additional extension of the range of power unit adjustment makes it possible to maintain the dispatch load curve and obtain profit for the electric power plant. The objective of this research is to carry out estimated and experimental processing of the operating regimes of the regeneration system of steam-turbine plants within the extended adjustment range and under the conditions when the constraints on the regeneration system and its equipment are removed. Constraints concerning the heat balance diagram that reduce the power unit efficiency when extending the adjustment range have been considered. Test results are presented for the nondeaerating heat balance diagram with the HTGZ turbine. Turbine pump and feed electric pump operation was studied at a power unit load of 120–300 MW. The reliability of feed pump operation is confirmed by a stable vibratory condition and the absence of cavitation noise and vibration at a frequency that characterizes the cavitation condition, as well as by oil temperature maintenance after bearings within normal limits. Cavitation performance of pumps in the studied range of their operation has been determined. Technical solutions are proposed on providing a profitable and stable operation of regeneration systems when extending the range of adjustment of power unit load. A nondeaerating diagram of high-pressure preheater (HPP) condensate discharge to the mixer. A regeneration system has been developed and studied on the operating power unit fitted with a deaeratorless thermal circuit of the system for removing the high-pressure preheater heating steam condensate to the mixer, with extending the range of load adjustment for the 300 MW power unit load.

Adjustment of honey load by honeybee pollen foragers departing from the hive: the effect of pollen load size

Honeybee foragers load a small amount of honey into the crop when they leave the hive. This “honey at departure” is used as a material to build pollen loads (glue honey) as well as fuel during flight in pollen foragers. We investigated the relationship between the size of pollen loads that a forager collected and the amount of honey at departure in the Western honeybee, Apis mellifera. Dancing pollen foragers increased honey at departure with the size of collected pollen loads. Analysis of the waggle-run duration revealed that the size of pollen load affected the rate of increase of honey at departure with food source distance in dancers. The increase rate was significantly higher in dancers that had returned to the hive with large pollen loads versus nectar-collecting dancers, but not in those with smaller pollen loads. The higher increase rate may reflect additional fuel carried for the return trip in pollen-foraging specialists that do not use collected nectar as fuel. Although honey carried by departing dance followers also increased significantly with the size of pollen load carried by dancers, the adjustment was different from that of dancers. These results suggest that recruited bees adjust the amount of honey at departure, including glue honey, based on communicated information and modify the amount of honey load subsequently based on their own experience.

Dynamic model for controller design of condensate throttling systems

Improving the load adjustment rate of coal-fired power plants in China is very important because of grid load fluctuations and the construction of new large-scale power plants connected to the country׳s power grid. In this paper, a new application of condensate throttling system for rapid load adjustment is proposed on the basis of the characteristics of turbine-stored energy. To ensure effective and safe operation of the condensate throttling system, a non-linear control model is derived through reasonable simplifications of fundamental physical laws, and the model parameters are identified using experimental data from a 660MW supercritical coal-fired power plant. The model outputs are compared with actual measured data for different unit loads. Results show that the established model׳s responses strongly correlate with the actual unit׳s responses and can be used for controller design.

A Single-Phase AC/DC Conversion Circuit with APFC

This system uses the MSP430F6638 and FPGA as the core, includes full bridge rectifier circuit, power factor correction circuit, Boost/Buck circuit and sample circuit. According to the sampling voltage and current value, The FPGA adjusts PWM wave duty ratio of power factor correction chip UC3854, completing single phase AC/DC conversion circuit with a voltage outer closed-loop and current inner closed-loop and active power factor correction (APFC). Test shows that the output voltage can stable in a setting value, with amplitude range ±0.05V, and when load’s impedance changes, this circuit can keep a small voltage adjustment rate and load adjustment rate. We use electronic parameter measurement device to measure the efficiency of AC/DC converter in a specified condition (voltage input Us=24V, current output Io=2A, voltage output Uo=36V), result demonstrates it’s a relatively ideal value. At the same time, under the control of UC3854, the power factor of alternating current input is 0.9734.And when we set the range of power factor between 0.8~1.0, The circuit can automatically adjust the power factor to track the set value.

Low-carbohydrate diet and type 2 diabetes risk in Japanese men and women: the Japan Public Health Center-Based Prospective Study.

ObjectiveEvidence is sparse and contradictory regarding the association between low-carbohydrate diet score and type 2 diabetes risk, and no prospective study examined the association among Asians, who consume greater amount of carbohydrate. We prospectively investigated the association of low-carbohydrate diet score with type 2 diabetes risk.MethodsParticipants were 27,799 men and 36,875 women aged 45–75 years who participated in the second survey of the Japan Public Health Center-Based Prospective Study and who had no history of diabetes. Dietary intake was ascertained by using a validated food-frequency questionnaire, and low-carbohydrate diet score was calculated from total carbohydrate, fat, and protein intake. The scores for high animal protein and fat or for high plant protein and fat were also calculated. Odds ratios of self-reported, physician-diagnosed type 2 diabetes over 5-year were estimated by using logistic regression.ResultsDuring the 5-year period, 1191 new cases of type 2 diabetes were self-reported. Low-carbohydrate diet score for high total protein and fat was significantly associated with a decreased risk of type 2 diabetes in women (P for trend <0.001); the multivariable-adjusted odds ratio of type 2 diabetes for the highest quintile of the score were 0.63 (95% confidence interval 0.46–0.84), compared with those for the lowest quintile. Additional adjustment for dietary glycemic load attenuated the association (odds ratio 0.75, 95% confidence interval 0.45–1.25). When the score separated for animal and for plant protein and fat, the score for high animal protein and fat was inversely associated with type 2 diabetes in women, whereas the score for high plant protein and fat was not associated in both men and women.DiscussionLow-carbohydrate diet was associated with decreased risk of type 2 diabetes in Japanese women and this association may be partly attributable to high intake of white rice. The association for animal-based and plant-based low-carbohydrate diet warrants further investigation.

A three-phase algorithm for state estimation in power distribution feeders based on the powers summation load flow method

State estimation approaches for use in transmission systems are common in the literature, however, there are few algorithms intended for distribution systems. This occurs, mainly, due to the small amount of measurement data available in real time and topological complexity of these systems. In this context, this paper proposes a new three-phase state estimation algorithm for radial distribution feeders, which is based on adjustment of loads from a dynamic utilization and imbalance factors, in order to model pseudo-measurements of powers, and take into account the imbalance of loads, frequently presents in feeders. The method performs the estimation by section, starting from the substation toward the loads, where estimated quantities in a section are used as pseudo-measurements to estimate the subsequent section. This procedure provides a computational optimization for real-time methodology presented here. Tests were performed in distribution feeders from a Brazilian power company and the results show satisfactory performance of developed state estimator in respect to adjustment of estimated values compared with corresponding real-time measured quantities.

Safety Analysis of a Solid Oxide Fuel Cell/Gas Turbine Hybrid System Fueled With Gasified Biomass

The effect of biomass gas on the safety performance of a solid oxide fuel cell (SOFC)/micro gas turbine (GT) hybrid system was studied with consideration of the fuel cell working temperature, fuel cell temperature gradient requirement, compressor surge zone, and turbine inlet temperature (TIT). The safety performance of the hybrid system on the design condition and off-design condition was also analyzed. Results show that the hybrid system is good adaptability to low concentrations of biomass gas. The electrical efficiency could reach 50% with different biomass gases and is higher than the other combined power systems that used biomass gas. The wood chip gas (WCG) would make the fuel cell or GT easier overheat than the other three gases. The cotton wood gas (CWG) and corn stalk gas (CSG) are easy to cause the TIT too low or the compressor surge. In the safety zone, considering the hybrid system load adjustment range, the effecting order (from large to small, following is same) is WCG, grape seed gas (GSG), CSG, and CWG. Considering the hybrid system electric efficiency, the effecting order is WCG, GSG, CWG, and CSG.

Evolution Balancing of the Small-Sized Wheel Loader Assembly Line

Assembly line balancing not only directly determines production efficiency but also influences precision and quality of key assemblies or even the overall performance of final products. Driven by market demand and development of science and technology, product family must evolve constantly, which necessitates frequent adjustment and rebalancing of product family assembly line (PFAL). In order to maintain production efficiency, improve assembly quality and precision, and reduce costs for adjustment, the evolution balancing problem of PFAL for small-sized wheel loader is solved in this paper. Firstly, the evolution balancing model of PFAL is put forward. Then, with minimizing the number of workstations, the in-station and between-station load indexes and adjustment costs, and maximizing relevancy between activities as optimization objectives, meanwhile regarding product platform planning, modularity design and the critical chain technology in concurrent engineering as constraint conditions, the evolution balancing problem of PFAL is optimized using improved genetic algorithm (IGA). Finally, the whole analysis procedure is demonstrated by the small-sized wheel loader PFAL case study and the effectiveness of the proposed method is verified.