Load Changes Research Articles

Maintaining reliability in a 100% decarbonized power sector: The interrelated role of flexible resources

Reliability will remain a key requirement for decarbonized power sectors, but also a concern with the high penetration of variable renewable energy (VRE). The traditional approach for reliability is by producing enough energy and adapting rapidly to changes in load with the dispatch of fossil fuel power plants, especially natural gas power plants. However, this will have to evolve as decarbonization progresses. Can various flexibility resources such as transmission, storage and demand response provide the same reliability benefits? This paper uses a detailed, capacity expansion and hourly operation model to investigate the possibility and the cost of reaching different levels of planning reserve margins (PRM), in the multi-regional context of the North American Northeast. We find that while it is possible to entirely avoid natural gas power plants or nuclear ones to obtain high PRM, it would come at a very high cost and would require high levels of transmission, storage and demand response. We also detail why these three flexibility resources are needed in combination. The implications for energy policies are significant: in order for power system's cost to remain reasonable, reliability must count on some carbon-neutral natural gas or nuclear generation, along with interties with neighboring systems, storage and high levels of demand response.

12553 Severe Hyperglycemia After Initiation Of Bictegravir Antiretroviral Therapy With Resolution Upon Discontinuation

Abstract Disclosure: S. Hudson: None. J. Aurora: None. K. Grossman: None. L. Kogelman: None. A.G. Pittas: None. Background: Antiretroviral therapy (ART) containing bictegravir (BIC), a second-generation integrase strand transfer inhibitor (INSTI), is a first-line treatment for HIV. There are mixed reports of INSTIs causing adverse metabolic effects, such as weight gain and hyperglycemia. There are cases of BIC causing hyperglycemia and diabetic ketoacidosis (DKA) within weeks to months following initiation; however, this has not been reported in clinical trials (1). It is unclear whether discontinuing BIC resolves hyperglycemia. We report a case of a patient with prediabetes who developed severe hyperglycemia after switching to a BIC-containing ART. The discontinuation of BIC resulted in significant improvement in glycemia, leading to the de-escalation of diabetes pharmacotherapy. Clinical Case: A 36-year-old woman with obesity was diagnosed with HIV during pregnancy, which was complicated by gestational diabetes mellitus. After pregnancy, she had prediabetes. Her initial ART was darunavir/cobicistat/emtricitabine/tenofovir alafenamide. Due to intolerable GI side effects, six years later, she was switched to bictegravir/emtricitabine/tenofovir alafenamide (BIC/FTC/TAF). Laboratory tests four months before starting BIC/FTC/TAF were consistent with prediabetes (HbA1c 6.4%, non-fasting blood glucose of 118 mg/dL). After one month, she was started on metformin when her HbA1c increased to 9.1% with a non-fasting blood glucose of 332 mg/dL. Another month later, HbA1c increased to 12.8% with a non-fasting blood glucose of 685 mg/dL without DKA. She was hospitalized for diabetes management. There were no significant changes in weight, viral load, or CD4 count. A search for secondary causes of hyperglycemia (diabetogenic medications, hypercortisolism, and autoimmune diabetes) was not revealing. She was discharged on metformin and insulin glargine. Her HIV regimen was switched to FTC/TAF and doravirine due to suspicion of BIC-induced hyperglycemia. After five months, she developed symptoms of hypoglycemia, and her estimated HbA1c by continuous glucose monitoring was 6.3%. Insulin glargine was discontinued. While on metformin, HbA1c three months later was 6.3%. Two years later on metformin and linagliptin: HbA1c was 6.1% and beta-cell function did not reveal insulin deficiency or resistance (non-fasting blood glucose 96 mg/dL, insulin 13.5 uIU/mL [RR 2.6-24.9 mIU/mL], C-peptide 3.7 ng/mL [RR 1.1-4.4 ng/mL]). Conclusion: Patients with HIV and a history of obesity and/or dysglycemia who are switched to a BIC-containing ART regimen should be educated and monitored for acute hyperglycemia. This may be due to impaired beta-cell function and/or insulin resistance; however, further research is needed to understand the mechanism. An alternative ART regimen should be considered if hyperglycemia develops. Reference: 1. Nolan NS, et al. Open Forum Infect Dis. 2021;16;8(5): ofab077. Presentation: 6/3/2024

Mechanical Characteristics of Deep Excavation Support Structure with Asymmetric Load on Ground Surface

The purpose of this paper is to capture the mechanical response of the support structure of deep excavation subject asymmetric load. A two-dimensional (2D) numerical analysis model was established by taking a pipe gallery deep excavation subject to asymmetric load as an example. The numerical analysis results were in good agreement with the measured data, thus verified the validity of the numerical model. On this basis, the stress and displacement of support structure caused by the change in foundation asymmetric load were studied. According to the numerical results, horizontal displacement of the diaphragm wall (DW) was dominant, and the maximum horizontal displacement of the DW was 7.54 mm when the deep excavation was completed. With the increase in asymmetric load, the left wall displacement continued to increase, while the displacement of the right DW continued to decrease, and the maximum horizontal wall displacement occurred near the excavation face. The DW was the main bending component, and the maximum wall bending moment when the deep excavation was completed was 173.5 kN·m. The maximum wall bending moment increased with the increase in asymmetric load, and the maximum wall bending moment on the left of the deep excavation was greater than that on the right. The inner support sustained the main component of axial force, with the axial force peaking at 1051.8 kN when the deep excavation was completed. The axial force of the inner support increased with increasing the asymmetric load, and the axial force of the second inner support was obviously greater than that of the first inner support. This research has a positive effect on the design and optimization of deep excavation support structure subject to asymmetric load on ground surface.

Dynamic simulation and control strategy development of molten salt steam generation system for coal-fired power plant flexible retrofit

The coal-fired power plant (CFPP) coupled with the molten salt thermal energy storage system is a potential way to improve its flexibility and peak-shaving ability. The steam generation system (SGS) is a suitable choice to convert the feed water into hot steam by using the heat from the molten salt. In this paper, the schematic of an SGS coupled with the CFPP is presented. A dynamic model of the SGS basing lump parameter method is established and validated to investigate its dynamic response characteristics. Five different disturbance experiments including feed water inlet parameters, molten salt inlet parameters and medium pressure steam valve, are conducted and analyzed. The dynamic response curves of molten salt and steam are obtained. Moreover, the load adjustment process of SGS with three different load changing rates (3 %, 6 %, 10 % Pe/min) under the rated conditions is compared and its influence on the SGS is analyzed. The temperature changing rates in the thick-wall components of SGS are within 2 °C/min which meets the safe operating standard. Based on the above results, the three elements control strategy with excellent robustness for the SGS safety operation is proposed and demonstrated. The results show that the response time for the SGS load regulation process and the water level fluctuation have been significantly improved as the three elements control strategy is imposed. The water level can be stabilized in 200 s with tiny fluctuation when the SGS loads down 10 % thermal load with 10 % Pe/min load changing rate. These results could provide useful references for the design and control strategy making of the CFPP coupled with the molten salt thermal energy storage system.

A multi-objective physiological control system for continuous-flow left ventricular assist device with non-invasive physiological feedback

In order to enable continuous-flow left ventricular assist device (CFLVAD) to adjust pump speed adaptively in response to changes in ventricular load, we developed a multi-objective physiological control system for CFLVAD with non-invasive physiological feedback mechanism, and proposed a multi-objective hierarchical control (MOHC) strategy to coordinate three controllers. A model-based estimation method was utilized to gain the physiological feedback variables. Suction prevention controller, regurgitation prevention controller, and physiological pulsatility controller were developed and applied to achieve the objectives: preventing left ventricular suction, preventing pump regurgitation, pump flow adaptive adjustment, and enhancing vascular pulsatility. The constraint conditions of feedback variables and controller priority were used to implement multi-objective hierarchical control. The preload and afterload were increased or decreased to simulate the scenarios of the sharp increase in left ventricular flow, the sharp decrease in left ventricular flow, and the rest-exercise-rest. The performance of MOHC was evaluated by subjecting it to three scenarios and compared with that of constant speed control (CSC) and pulsatile varying speed control (PVSC). The simulation results show that the linear correlation between the filtered and actual feedback variables was as high as 99.9%. Compared with CSC and PVSC, MOHC can avoid ventricular suction and pump regurgitation when the left ventricular flow changed rapidly. During rest or exercise, MOHC provided more adequate physiological perfusion and enhances greater vascular pulsatility than CSC and PVSC. MOHC can adjust the CFLVAD pump speed in response to changes in ventricular load.

An analytical solution to ground stresses induced by tunneling considering ground surface boundary conditions and gravity

Accurately predicting the stress distribution around the tunnel is crucial for designing safe and economical support systems. The stress distribution is closely related to the ground stress release induced by tunneling, as well as the initial gravity stress and boundary conditions. In this study, a two-dimensional analytical model considering the ground surface boundary conditions and gravity is presented to investigate the stress field around the tunnel. Then, a numerical model was developed to validate the proposed analytical model. Finally, parametric analyses were conducted, and the limitations of the load calculation method of the code for design of shield tunnel in China were discussed. The results indicate that: (a) Tunnel excavation induces stress redistribution in the soil, resulting in a soil arching effect around the tunnel. This arching effect causes nonlinear load changes around the tunnel. (b) The soil mass around the tunnel can be divided into undisturbed and disturbed zones. Above the tunnel, the disturbance range is C-2D(C and D represent the burial depth and the tunnel diameter), while below and on both sides of the tunnel, the disturbance ranges are 4D and 1.5D, respectively. (c) Once the stress release rate reaches 0.6, a combined arching effect zone, consisting of both major and minor principal stresses, is formed in the disturbance zone above and below the tunnel. (d) The load distribution pattern calculated by the code for design of shield tunnel in China is gourd-shaped, and this calculation method is insufficient for accurately evaluating the load around the tunnel. The research results can provide a reference for the design of the shield tunnel.

Comparison of Weekly Training Load and Acute: Chronic Workload Ratio Methods to Estimate Change in Training Load in Running.

Before examining the impact of training load on injury risk in runners, it is important to gain insight into the differences between methods that are used to measure change in training load. To investigate differences between 4 methods when calculating change in training load: (1) weekly training load; (2) acute : chronic workload ratio (ACWR), coupled rolling average (RA); (3) ACWR, uncoupled RA; (4) ACWR, exponentially weighted moving average (EWMA). Descriptive epidemiology study. This study is part of a randomized controlled trial on running injury prevention among recreational runners. Runners received a baseline questionnaire and a request to share global positioning system training data. Runners who registered for running events (distances 10-42.195 km) in the Netherlands. The primary outcome measure was the predefined significant increase in training load (weekly training loads ≥ 30% progression and ACWRs ≥ 1.5), based on training distance. Proportional Venn diagrams visualized the differences between the methods. A total of 430 participants (73.3% men; mean age = 44.3 ± 12.2 years) shared their global positioning system training data for a total of 22 839 training sessions. For the weekly training load, coupled RA, uncoupled RA, and EWMA method, respectively, 33.4% (95% CI = 32.8, 34.0), 16.2% (95% CI = 15.7, 16.6), 25.8% (95% CI = 25.3, 26.4), and 18.9% (95% CI = 18.4, 19.4) of the training sessions were classified as significant increases in training load. Of the training sessions with significant increases in training load, 43.0% from the weekly training load method were different than the coupled RA and EWMA methods. Training sessions with significant increases in training load based on the coupled RA method showed 100% overlap with the uncoupled RA and EWMA methods. The difference in the change in training load measured by weekly training load and ACWR methods was high. To validate an appropriate measure of change in training load in runners, future research on the association between training loads and running-related injury risk is needed.

An Internet of Things Task Scheduling Framework Based on Agile Virtual Network on Demand Service Model

In order to improve the efficiency of cloud computing resource utilization and avoid the problem of computing resource allocation and scheduling lagging behind load changes, the author proposes a cloud computing resource on-demand allocation and elastic scheduling method based on network load prediction. Firstly, the author takes the network load data of Wikimedia as the research object and proposes an adaptive two-stage multi network model load prediction method based on LSTM, i.e. ATSMNN-LSTM load prediction method). This method can classify the network load data into climbing and descending types based on the trend and characteristics of the input network load data, And adaptively schedule the input network load data to the LSTM load prediction model that matches its type for prediction based on the classification results. The author proposes a maximum cloud service revenue computing resource quantity search algorithm based on network load prediction (i.e. MaxCSPRNWP algorithm), which aims to improve cloud service revenue as the optimization objective. Under the premise of ensuring task service quality and system stability, the algorithm allocates cloud computing resources on demand and flexibly schedules them in advance based on the predicted network load results. The experimental results show that the ATSMNNLSTM load prediction method proposed by the author can obtain more accurate network load prediction results compared to other load prediction methods, and the MaxCSPR-NWP algorithm, which is based on network load prediction and is capable of effectively converting the network load prediction results into the required number of cloud servers, is the maximum cloud service revenue computing resource quantity search algorithm proposed by the author, not only does it achieve the early allocation and scheduling of cloud computing resources, thereby avoiding the impact of lagging behind in computing resource allocation and scheduling due to load changes on the quality of cloud computing task services and resource utilization efficiency, at the same time, it has also achieved on-demand allocation and flexible scheduling of cloud computing resources with the goal of improving cloud service revenue.

Study of correlation between arches of foot and lower back pain in Eastern India

Background: Low back pain is one of the most common disorders of the musculoskeletal system, leading to impaired function and decreased quality of life in many patients. Foot arch alterations may lead to structural changes and/or affect its load distribution. It should be noted that even slight elevations of the foot’s medial longitudinal arch above the norm may lead to changes in load and pressure distribution. Hence, it becomes important to find the relationship between low back pain and altered foot arch indices leading to improper body balance. Aims and Objectives: The aims and objectives of the study are to find any correlation between lower back pain and an altered foot arch index in the Eastern Indian population. Materials and Methods: A total of 60 subjects aged 20–40 years with varying degrees of low back pain were selected. Low back pain scores of the subjects were found using modified oswestry low back pain disability questionnaire. Footprints in standing position using ink were taken on graph paper and the foot arch indices were calculated. Results: 54.16% of the male and 36.11% of female participants had low arched feet, 20.83% of male and 52.78% of female participants had normal arched feet, and 25% of male and 11.11% of female participants had high arched feet with varying degrees of low back pain. 77.42% of the participants with minimal disability due to low back pain were having normal arched feet, 71.43% of the participants with moderate disability due to low back pain were having low arched feet, and 100% of the participants with severe disability due to low back pain were having either high or low arched feet. Conclusion: This study showed that people having either low or high arched feet are at an increased risk of developing acute or chronic low back pain at some stage in their lives. Knowledge of this risk factor might even help people to choose appropriate occupations in the future.

Study on the influence of sediment erosion of Francis turbine runner under different water heads

Abstract The average measured sediment concentration of the river section where Wanjiazhai Hydropower Station is located over the years is 5.7kg/m 3, The maximum measured sediment concentration reaches 37.6kg/m 3, The erosion of the flow components of hydraulic turbines caused by sand containing water flow is becoming increasingly severe, coupled with the frequent impact of load changes during peak shaving operation, the problems exposed during the operation of hydraulic turbines are becoming more prominent, which affects the stable operation of the units. This article uses numerical simulation and experimental testing to study the sediment wear characteristics and hydraulic performance of the water turbine at Wanjiazhai Hydropower Station. Research has revealed the effects of working head on impeller wear. The increase in working head will exacerbate the impact wear on the main channel wall of the unit. The surface of water turbine blades is the main wear area, and the high-speed impact of particles causes an increase in the wall wear rate. The probability of particles coming into contact with the wall at the outlet increases, resulting in rapid wear at this point. The increase in head will intensify the wear intensity of the unit surface, and the flow velocity in the gap indicates that the local high-speed jet in the gap is the main cause of gap wear. Therefore, in order to ensure the efficient anti-wear performance of the water turbine, multiple factors need to be comprehensively considered to cope with sediment wear of the water turbine, including regular cleaning, optimized structural design, use of wear-resistant materials, replacement of worn parts, and optimization of operating parameters. These measures help to reduce the damage of sediment wear to water turbines and extend their service life.

Assessment of mechanical variables best describing bone remodelling responses based on their correlation with bone density

Density distribution in bones can be estimated using bone remodelling models (BRM) and applying daily normal loads to assess the stress/strain state to which the bone is subjected. These models locally relate a certain mechanical stimulus, derived from the stress/strain state, directly to bone density or to its variation over time. The background of this idea is Frost’s Mechanostat Theory, which states that overloading states tend to increase bone density and disuse states tend to decrease it. Different variables have been proposed in the literature to measure the mechanical stimulus. Strain energy density (SED) and stresses have been commonly used as mechanical stimuli, but to date their use has not been justified with convincing arguments. In this paper we have selected several variables derived from stress and strain tensors and correlated them with the distribution of bone density in the femur of 13 elderly women to conclude which would be most appropriate for use as a mechanical stimulus in a BRM. We have performed this correlation analysis for six different activities: walking normally, fast walking, stair ascent, stair descent, rising from and sitting on a chair, and jumping in place. Musculoskeletal models were used to estimate joint reaction and muscle forces of each individual for each activity. These were applied to the corresponding finite element model of the femur to obtain stress and strain tensors at each point. The variables proposed as mechanical stimulus and derived from these tensors were correlated to the actual density obtained for each individual from CT-scans. Our results show that stress variables are the best correlated with density. In contrast, the correlations of SED are very weak, so it is not a good candidate for mechanical stimulus. Strains are also weakly correlated to density, but in this case because their distribution across the femur is rather uniform. This is in agreement with the Mechanostat Theory which states that bone reacts to load changes by changing its stiffness so to keep strains in a certain interval. Consequently, a plausible choice for a remodelling criterion could be keeping that strain uniformity.

Proportional Integral Type Sliding Function For DC-DC Boost Converter In Solar Power System

Background: DC-DC Boost Converters are crucial components in solar power systems, requiring effective control for optimal performance. This paper introduces an adaptive sliding mode controller with a modified sliding function to overcome the limitations of classic sliding mode control in DC-DC boost converters. Materials and Methods: The study presents a detailed mathematical model of the DC-DC boost converter and derives a state-space representation. A Proportional-Integral (PI) type sliding function is proposed, introducing an additional tuning parameter γ that can be adaptively adjusted based on load variations. The control law and existence conditions for sliding modes are established, demonstrating the robustness of the proposed method to load changes. Results: Simulation results compare the performance of the proposed PI-type sliding mode control (SMC) with classic SMC for a DC-DC boost converter under varying load conditions. The PI-type SMC demonstrates superior dynamic performance, recovering from a sudden load change in 10 ms compared to 30 ms for classic SMC. Conclusion: The proposed PI-Type Sliding Function for DC-DC Boost Converters in solar power systems offers improved adaptability to load variations and faster dynamic response, potentially enhancing the efficiency and reliability of solar power systems.

A New Stochastic Controller for Efficient Power Extraction from Small-Scale Wind Energy Conversion Systems under Random Load Consumption

This paper presents an innovative scheme to enhance the efficiency of power extraction from wind energy conversion systems (WECSs) under random loads. The study investigates how stochastic load consumption, modeled and predicted using a Markov chain process, impacts WECS efficiency. The suggested approach regulates the rectifier voltage rather than the rotor speed, making it a sensorless and reliable method for small-scale WECSs. Nonlinear WECS dynamics are represented using Takagi–Sugeno (TS) fuzzy modeling. Furthermore, the closed-loop system’s stochastic stability and recursive feasibility are guaranteed regardless of random load changes. The performance of the suggested controller is compared with the traditional perturb-and-observe (P&O) algorithm under varying wind speeds and random load variations. Simulation results show that the proposed approach outperforms the traditional P&O algorithm, demonstrating higher tracking efficiency, rapid convergence to the maximum power point (MPP), reduced steady-state oscillations, and lower error indices. Enhancing WECS efficiency under unpredictable load conditions is the primary contribution, with simulation results indicating that the tracking efficiency increases to 99.93%.

Water and Thermal Management in PEM Fuel Cells Using Feasible Humidity Plots and Model Predictive Controllers

Water and thermal management are critical for the performance, efficiency and longevity of PEM fuel cells (PEMFCs). Effective water and thermal management require the design of control systems that can maintain the water balance and temperature at stable and optimal levels. In this paper, we consider a stack of PEM fuel cells integrated with a water recovery and cooling system. A mechanistic dynamic model is developed to be able to predict the water content and temperature in response to the fuel cell inputs. Water management uses a cascade arrangement of a supervisory Model Predictive Controller (MPC) and local anode and cathode PID humidity controllers to balance the membrane water content. Thermal management consists of a separate MPC controller to regulate the fuel stack temperature. One novelty of this work lies in identifying and utilizing the feasible region for the relative humidities of the anode and cathode when controlling the membrane water content. We introduce the feasible humidity plots (FHP) which define the feasible values for the anode and cathode relative humidities for a given fuel cell design and its operating conditions. This useful information helps to assign the set-point values to the local PID humidity controllers of the water management system. It is shown by simulations that the water and thermal management MPC controllers work in tandem and successfully track the desired set-point changes in humidity and temperature while rejecting external disturbances such as load changes. In addition, the control system is robust against modeling errors and possible model-plant mismatch introduced by fuel cell aging.

Voltage stability control strategy for DC microgrid based on adaptive virtual DC motor

The large-scale integration of distributed energy sources and power electronic devices results in the DC microgrid exhibiting significant low inertia and weak damping characteristics. This, in turn, leads to inevitable fluctuations in the DC bus voltage, which endanger the stable operation of the DC system. Energy storage devices can provide equivalent inertia. To enhance the inertia and response speed of the DC bus interface converter, this paper proposes a power allocation parameter adaptive virtual DC motor control strategy based on a hybrid energy storage unit. The strategy introduces power allocation control to regulate the energy storage converter on the basis of virtual inertia parameter adaptive control, thereby enabling the energy storage converter to simulate the inertia and damping characteristics of a DC generator. The small-signal stability of the system is analyzed by establishing a small-signal model of the photovoltaic energy storage system and utilizing the impedance ratio criterion. Finally, the proposed control strategy is validated through simulation. The results demonstrate that the strategy effectively mitigates the fluctuations in bus voltage under varying photovoltaic power and sudden load changes, ensures the power distribution in the hybrid energy storage system, and enhances the dynamic response of the system.

Constraining the origin of the Norwegian strandflat – The influence of isostatic and dynamic surface changes

The Norwegian strandflat is a prominent low-relief bedrock surface found near sea level along most of the west coast of Norway. Its origin has been discussed throughout the last 130 years but is yet to be resolved. Some studies suggest that the strandflat represent a tropical weathering front of Mesozoic age that has since been buried and re-exhumed, while others relate its origin to Pleistocene periglacial and glacial processes and/or wave-induced weathering and erosion. Previous interpretations of the strandflat have considered postglacial isostatic uplift, but the impacts of isostatic changes due to glacial erosion and deposition, as well as dynamic surface changes driven by mantle convection, have been largely overlooked. Here we examine how geomorphological-driven isostatic changes and dynamic surface changes have influenced the land-surface elevation along the Norwegian coast during late Pliocene-Quaternary (the last ca. 3 million years). We employ quantitative estimates of glacial erosion and deposition to assess the flexural isostatic response from the resulting load changes. Our analyses show that patterns of geomorphic isostatic adjustments and dynamic surface changes are generally not reflected in the present elevation of the strandflat. Only the loading effect from the deposition of the North Sea Fan can clearly be correlated with the submerged strandflat found near Stad (~62 °N). Our results imply that if the strandflat formed synchronously along the Norwegian coast as a flat surface at sea level, the strandflat we observe today must have developed after the majority of late Pliocene-Quaternary glacial erosion took place, but prior to the main deposition of the North Sea Fan. This would place strandflat formation within the last few glacial cycles, but before the Last Glacial Maximum (LGM). This inferred pre-LGM age of the strandflat is generally consistent with cosmogenic nuclide exposure ages and observed striations on the strandflat. Finally, we examine ice cover and land-surface changes relative to sea level during the last 80,000 years and find no extended periods favorable for synchronous strandflat formation across all regions along the Norwegian coast. This implies that either the strandflat is diachronous, or that the processes of formation have either been extremely fast under certain conditions or are independent of sea level, for instance related to glacial erosion.

Emulation tests of dynamics and control for a turbocharged SOFC system

This work regards experimental emulation activities for a Solid Oxide Fuel Cell (SOFC) pressurized by a turbocharger, focusing attention on the control system validation. The SOFC-based plant considered here was developed to couple high efficiency (due to pressurization) with reasonable capital costs. In detail, significant cost decrease (against SOFC hybrid plants including a microturbine) can be obtained with a turbocharger, due to large mass manufacturing process for these machines. Moreover, to pursue the zero emission target, the system was sized to operate with a renewable source fuel (biogas).Since this system has integration problems due to critical dynamic and control aspects, the University of Genoa designed and installed an experimental facility based on the coupling between a pressure vessel with a commercial turbocharger. The fuel cell is emulated equipping the vessel with a burner (to obtain the SOFC temperature range) and with inert ceramic material (to generate the same dynamic response).The tests presented in this work were obtained with this emulation rig operated in cyber-physical mode: the hardware interacted in real-time mode with previously validated software for components not physically included in the rig. The results demonstrated the system feasibility for load changes and validated the proposed control system, showing robustness and good prevention of critical conditions, such as SOFC thermal stress.

A cooperative distributed droop gains adjustment in DC microgrids

Direct Current (DC) microgrids are a very promising solution to integrate renewable energy sources, energy storage systems and loads. The main goals of a microgrid controller are to achieve voltage regulation and load sharing among multiple distributed generators (DGs). Distributed control techniques are widely adopted to address these two objectives. Most of the existing distributed methods in the literature adjust the deviation caused by the conventional droop control by adding two additional terms. In this work, a new cooperative distributed controller to adjust the droop gains of DGs is proposed. The proposed method achieves average voltage regulation and proportional current sharing in a unified manner. It does not require additional corrective terms, resulting then in a simple control structure. Moreover, it relies only on exchanging one communication variable among neighboring DGs, which reduces the communication overhead. The stability of the proposed controller is analyzed using a small signal model of the system. The effectiveness of the proposed controller is evaluated under common load changes, local load variations, communication link failures and communication delays. The designed control scheme is verified through Hardware-In-the-Loop (HIL) tests using NI PXIe real-time simulator.

Clinical efficacy and safety of new compound single tablet antiviral drugs in the treatment of HIV/AIDS

AimsGenvoya, Biktarvy and Dovato are novel single-tablet antiretroviral therapy(ART). The aim of this study is to explore the therapeutic effects of these novel drugs on HIV/AIDS. Main methodsThis retrospective cohort study, conducted at a single center, included a total of 200 HIV-treated patients who transitioned to these new antiretroviral drugs from July 2021 to August 2023. Data were extracted from electronic medical records at Ditan Hospital. The Genvoya group comprised 22 patients, and all subsequent switches in this group were to Biktarvy. The primary HAART group consisted of 178 patients initially treated with a first-line triple Highly Active Antiretroviral Therapy (HAART) regimen during the same period. This group was further subdivided into HAART+Dovato, HAART+Biktarvy, and HAART+Genvoya groups based on the switching regimen. The primary outcomes focused on changes in viral load and immune efficacy, while secondary safety indicators included blood/liver function, lipid parameters, renal function, blood glucose, blood uric acid, etc. Key findingsThe viral suppression rate was 100 % after the drug change treatment, and CD4+ T cell counts increased significantly across all four groups. Over the 6-month treatment period, there were increases in creatinine (Cr), low-density lipoprotein (LDL), high-density lipoprotein (HDL), erythrocyte count, and glomerular filtration rate (eGFR). Conversely, Alanine transaminase (ALT), Aspartate aminotransferase (AST), C-reactive protein (CRP), albumin (ALB), and blood glucose (Glu) levels decreased. SignificanceGenvoya, Biktarvy and Dovato are recommended for the treatment of HIV/AIDS and have a good safety profile.

ID: 329069 Change in brain amyloid load in a prodromal alzheimer’s disease patient after low-intensity ultrasound treatment

ID: 329069 Change in brain amyloid load in a prodromal alzheimer’s disease patient after low-intensity ultrasound treatment