Daily Output Research Articles

Multi-Scheme Optimal Operation of Pumped Storage Wind–Solar–Thermal Generation System Based on Tolerable Energy Abandonment

In multi-energy complementary power generation systems, the complete consumption of wind and photovoltaic resources often requires more costs, and tolerable energy abandonment can bring about the more reasonable optimization of operation schemes. This paper presents a scheduling model for a combined power generation system that incorporates pumped storage, wind, solar, and fire energy sources. Through a comparison of schemes, the energy regulation function of the pumped storage power station was verified and analyzed. The CPLEX solver and MOPSO algorithm were employed to solve the daily output of a pumped storage power station in the Gansu region under various scenarios. The incorporation of pumped storage power plants has the potential to provide many benefits, including a reduction in operating expenses by about CNY 1.1163 million, a decrease in carbon emissions by 491.24 t, an enhancement in the stability of thermal power by 2.39%, and an improvement in the combined system capability to absorb additional energy. The correlation between the indicators of the combined system and the penetration rate of renewable energy is non-linearly influenced by changes in the power capacity configuration. Ultimately, the multi-objective optimization computation yields the ideal operational scheme for each power source, taking into account a tolerable energy abandonment mode.

Performance assessment of a novel solar distiller with a fountain-shaped basin design embedded with phase change materials enriched with copper oxide nano-additives: A detailed experimental investigation

This study uses a novel structure of a dome-shaped solar distiller (DSD) with a stepped conical absorbent basin with multi-trays instead of the typical flat absorbent basin solar stills to enhance the evaporation and exposure areas. Moreover, a fountain seawater feed supply system is also centrally integrated into the developed basin to reduce the saltwater film thickness on the stepped conical trays for enhancing the heating processes of seawater over the trays' surfaces. Meanwhile, a phase change material enriched with CuO nanoparticles (NCPCM) is also embedded inside the hollow multi-tray stepped conical basin to prolong the distiller's nightly yield. Three DSDs are piloted and investigated: a dome-shaped solar distillatory with a fountain feed supply and nanocomposite (DSD-FFS + NCPCM), a dome-shaped solar distillatory with a fountain feed supply (DSD-FFS), and reference dome-shaped solar distiller (RDSD). The findings showed that the daily product output was 7.21 kg/day/m2 for DSD-FFS + NCPCM and 6.84 kg/day/m2 for DSD-FFS. In contrast, the RDSD achieved a daily product output of 4.44 kg/day/m2. This represents a significant improvement of 62.38 % and 54.05 % for DSD-FFS + NCPCM and DSD-FSS, respectively, over RDSD. Furthermore, the daily energic efficacity for DSD-FFS + NCPCM and DSD-FFS was evaluated at 62.42 % and 60.40 %, respectively, indicating an augmentation rate of 59.61 % and 53.56 % over RDSD. More so, the distiller exergy efficiency for DSD-FFS + NCPCM and DSD-FFS reached 4.16 % and 3.59 %, respectively, signifying an increase percentage of 123.66 % and 98.39 % over RDSD. Additionally, the cost analysis revealed that the price per 1 kg of distillate of the DSD-FFS + NCPCM and DSD-FFS declined by 18.48 % and 16.13 % over RDSD.

Performance enhancement of hemispherical distillers using copper chips and paraffin wax as energy storage integrated with an external condenser

Three hemispherical solar still (HSS) models were compared in this study: a conventional (CHSS), one modified (MHSS) to use various types of heat storage materials, and the latter modified with an external condenser (MHSSC). In addition, three cases of different heat storage materials: (I) copper chips with reduced graphene oxide (rGO), (II) copper chips with (rGO) and paraffin wax as phase change material (PCM), and (III) copper chips with rGO and PCM involving copper chips were put to the test, and their results were compared with regard to system temperatures, hourly yield, daily production, thermal performance, and price per freshwater litre. Copper chips are combined with rGO and paraffin wax to augment the thermal properties of CHSS, and the external condenser was used to increase the freshwater through enhancing the condensation rate. The results demonstrated that case III showed the greatest improvement from both the freshwater output and thermo-economic viewpoints. Also, in this instance, for this case, with daily freshwater output and energy efficiency of 6.89 L/m2 and 66.82 %, respectively, MHSSC outperformed CHSS by 118.73 % and 118.22 %. Moreover, the diurnal exergy efficiency with the greatest value was 3.88 % for MHSS, which implies an improvement of 144.03 %. Finally, for MHSS and MHSSC, the cost for generating one litre of fresh water was 0.025 and 0.028 $/L, with freshwater cost reductions of 32.43 and 24.32 %, respectively.

Spatially-assembled binary carbon anode synergizing directional electron transfer and enriched microbe accommodation for wastewater treatment and energy conversion: From simulation to experiments

Bioelectrochemical systems (BESs) hold prospects in wastewater energy and resource recovery. Anode optimization is important for simultaneous enhancement of wastewater energy conversion and effluent quality in BESs. In this study, a multi-physics model coupling fluid flow, organic degradation and electrochemical process was constructed to guide the design and optimization of BES anodes. Based on the multi-physics simulation, spatially-assembled binary carbon anodes composed of three-dimensional carbon mesh skeleton and granular activated carbon were proposed and established. The granular activated carbon conducive to microbe accommodation played a vital role in improving effluent water quality, while the carbon mesh skeleton favoring electron collection and transfer could enhance the bioelectricity output. With an average chemical oxygen demand (COD) removal rate of 0.442 kg m−3 d−1, a maximum power density of 20.6 W m−3 was achieved in the optimized composite anode BES, which was 25% and 154% higher than carbon mesh skeleton BES and granular activated carbon BES. Electroactive bacteria were enriched in composite anodes and performed important functions related to microbial metabolism and energy production. The spatially-assembled binary carbon anode with low carbon mesh packing density was more cost-effective with a daily energy output per anode cost of 221 J d−1 RMB−1. This study not only provides a cost-efficient alternative anode to simultaneously improve organic degradation and power generation performance, but also demonstrates the potential of multi-physics simulation in offering theoretical support and prediction for BES configuration design as well as optimization.

Enhancement in the performance of closed loop inclined wick solar still by attaching external bottom reflector

A closed-loop inclined wick solar still containing an external bottom reflector (CLIWSSR) has been proposed in this work. The attached bottom reflector, when positioned at an optimum angle, increases the amount of solar radiation that strikes the wick. As a result, the overall amount of distillate which the solar still produces has increased. The mathematical model of CLIWSSR has been created and validated. The optimum average tilt angle (OATA) of the inclination of the reflector has been determined for various months in Raipur, Chhattisgarh, India (21.2514° N, 81.6296° E). The OATA of the bottom reflector for the summer months is about 48.5o, whereas for winter months it is about 26.1o. The daily distillate output produced by proposed system (CLIWSSR) in a typical winter day (21/02/2023) for Raipur is 6.106 kg/m2 whereas the daily distillate output in same day of CLIWSS without reflector is 5.047 kg/m2. The daily output produced from CLIWSSR is about 21% more than the CLIWSS without reflector. The proposed design is simple, giving higher performance and an effective way to address the need of pure water in remote and small towns.

Assessment of Solar Energy with Respect to Bihar: A Case Study

A well-known statistical simulation method known as ARIMA was employed in this article to forecast the total daily solar energy output till the year 2040. The ARIMA model’s attractiveness resides in its simplicity, solar energy, which is created by sunshine, is a non-depleting renewable energy source that is unpolluting. The amount of solar energy that enters the earth every hour is sufficient to supply all of the energy needed for a year. In the modern period, we required electricity constantly. This solar energy is produced for use in commercial, industrial, and residential settings. It is simple to collect energy from direct sunshine. As a result, it is incredibly effective and does not pollute the environment. In this paper, we evaluated solar energy from sunlight and forecasted the sun radiation till 2040 through ARIMA Model.The model is created using sophisticated statistical approach. Error analysis is performed to demonstrate the effectiveness of the proposed method. The developed model’s accuracy can be improved in future research.

Artificial neural network modeling of solar photovoltaic panel energy output

Solar panel energy output is an essential parameter for the design and operation of renewable energy systems. Previously, little was known about the precise relationship between the energy outputs of solar panels with various meteorological, radiometric, and weather conditions in the southern California region. Without precise modeling or prediction systems, solar energy can potentially be wasted due to grid energy fluctuation. Thus, it is intended to use an artificial neural network (ANN) to develop solar panel energy output prediction model with a high degree of accuracy. A self-developed feedforward ANN model utilizing the Rectified linear unit (ReLu) activation function was used in the present study. Meteorological, weather, and sun irradiation data collected throughout the last year from a residential location have been used to train the models. The model’s performance was identified based on the minimum mean absolute error (MAE) and root mean square error (RMSE) and maximum linear correlation coefficient (R2). Further, the present self-developed ANN model was consistent with other solar energy experimental results and theoretical analysis. The developed ANN model using the Python programming language achieved a high R2 of more than 85% which ascertains the accuracy and suitability of the model to predict the daily solar energy output in local southern California area. This ANN modeling approach can be extended to many other applications such as SCORE, commercial, and residential building design.

Short-term forecasting approach of single well production based on multi-intelligent agent hybrid model.

The short-term prediction of single well production can provide direct data support for timely guiding the optimization and adjustment of oil well production parameters and studying and judging oil well production conditions. In view of the coupling effect of complex factors on the daily output of a single well, a short-term prediction method based on a multi-agent hybrid model is proposed, and a short-term prediction process of single well output is constructed. First, CEEMDAN method is used to decompose and reconstruct the original data set, and the sliding window method is used to compose the data set with the obtained components. Features of components by decomposition are described as feature vectors based on values of fuzzy entropy and autocorrelation coefficient, through which those components are divided into two groups using cluster algorithm for prediction with two sub models. Optimized online sequential extreme learning machine and the deep learning model based on encoder-decoder structure using self-attention are developed as sub models to predict the grouped data, and the final predicted production comes from the sum of prediction values by sub models. The validity of this method for short-term production prediction of single well daily oil production is verified. The statistical value of data deviation and statistical test methods are introduced as the basis for comparative evaluation, and comparative models are used as the reference model to evaluate the prediction effect of the above multi-agent hybrid model. Results indicated that the proposed hybrid model has performed better with MAE value of 0.0935, 0.0694 and 0.0593 in three cases, respectively. By comparison, the short-term prediction method of single well production based on multi-agent hybrid model has considerably improved the statistical value of prediction deviation of selected oil well data in different periods. Through statistical test, the multi-agent hybrid model is superior to the comparative models. Therefore, the short-term prediction method of single well production based on a multi-agent hybrid model can effectively optimize oilfield production parameters and study and judge oil well production conditions.

A New Experimental Method for Acid Pretreatment in Perforated Horizontal Wells: A Case Study of Mahu Conglomerate Reservoir

The Mahu Oilfield in Xinjiang, China, is the world’s largest conglomerate oilfield, with a daily output of more than 8000 tons. In the fracturing of perforated horizontal wells, the breakdown pressure is high, resulting in difficulties in their treatment. Acid pretreatment has been applied to reduce the breakdown pressure in the field, but with poor performance. Few studies have been conducted on how acid pretreatment affects the breakdown pressure under perforation conditions in the Mahu conglomerate reservoir. Also, existing fracturing or acid pretreatment experiments cannot simulate perforation well. Therefore, a new method was developed to make perforations by hydro jetting the fracturing specimens (300 mm × 300 mm × 300 mm) first. It can achieve specified perforation parameters, including the perforation angle, position, and length. Subsequently, true triaxial hydraulic fracturing experiments were conducted on the conglomerate specimens obtained from the Mahu area. The effects of the acid pretreatment on the fracture initiation and breakdown pressure were investigated by injecting the perforation section of the conglomerate using various acid systems. The study results showed that the perforation made by the new apparatus was extremely close to the perforation on-site. The acid pretreatment effectively dissolved minerals and could decrease the breakdown pressure down to 7.7 MPa. A combination of 6%HF + 10%HCl was recommended for the acid pretreatment in the Mahu conglomerate reservoir. A total of 60 min acid–rock contact time is necessary for sufficient rock dissolution. The mechanism of the acid pretreatment to decrease the breakdown pressure is that the rock dissolution by the acid reduces the rock tensile strength and increases the permeability. The raised permeability increases the fluid pressure of the reservoir near the wellbore so as to reduce the breakdown pressure of the formation. The research results provide technical support for reducing construction difficulty and optimizing parameters in the Mahu Oilfield.

The outflow characteristics of PV water lifting systems based on multiple tracking strategies

In order to clarify the problems of high failure rate, low efficiency, and low outflow rate of PV water pumping stations in pastoral areas due to large differences in resource conditions and poor equipment matching, this study uses the PV water supply model, establishes a pilot site for PV human storage water supply in pastoral areas, carries out research on the relationship between solar energy resources, water supply demand and power system of PV water pumping stations based on group observation tests in the field, and analyzes the PV system. We analyzed the relationship between different tracking operation modes and the amount of solar radiation and water supply flow, and compared the outflow characteristics of fixed type, single-axis tracking type, and double-tracking axis type, in order to explore a kind of PV water pumping station technology suitable for human storage and drinking water in pastoral areas, which can meet the water demand of pastoral water users. The research results show that the single-axis and dual-axis water lifting systems are significantly more efficient than the fixed-support water lifting system, receiving solar radiation at more than 80% of the maximum radiation throughout the day, and lifting water flow at more than 90% of the maximum discharge flow. Compared with the fixed-support PV water lifting system, the radiation of the single-axis PV water lifting system increases by 28.9%, and the daily water output increases by 43%; for the dual-axis PV water lifting system, compared with the single-axis PV water lifting system, the daily radiation of the dual-axis PV water lifting system increased by 4.8% and the daily water output increased by 3.2%; the starting radiation of the PV water lifting system was 256 W/m2.

Diurnal cortisol, neuroinflammation, and neuroimaging visual rating scales in memory clinic patients

AbstractBackgroundNeuroinflammation is considered a hallmark of the Alzheimer’s disease (AD) pathogenic process. Dysregulations in stress hormones (cortisol) may increase AD risk and are related to brain atrophy. This cross‐sectional study aims to examine interactions of cortisol patterns and neuroinflammation markers in their association with neuroimaging correlates.Method188 participants were recruited from the Karolinska University Hospital memory clinic (Stockholm, Sweden), and underwent magnetic resonance imaging or computed tomography. Four visual rating scales were applied to the scans: medial temporal lobe atrophy (MTA), global cortical atrophy (GCA), white matter lesions (Fazekas), and posterior atrophy (Koedam). Additionally, participants provided saliva to assess diurnal cortisol patterns, and underwent lumbar punctures for cerebrospinal fluid (CSF) sampling. Five cortisol measures were used: awakening levels, bedtime levels, cortisol awakening response (CAR), total daily output, and the ratio of awakening to bedtime levels (AM/PM ratio). Nineteen CSF neuroinflammation markers were categorized into five composite scores (mean z‐scores): proinflammatory cytokines (Interleukin (IL‐)6, IL‐8, IL‐15, IL‐12/IL‐23 p40, CC chemokine ligand (CCL)4, CXC chemokine ligand 10), other cytokines (IL‐5, IL‐16, CCL17), angiogenesis markers (Vascular endothelial growth factor (VEGF), VEGF‐D, VEGF‐receptor 1, Placental growth factor), vascular injury markers (Serum amyloid A, C‐reactive protein, Vascular cell adhesion molecule‐1, Intercellular adhesion molecule‐1), and glial activation markers (YKL‐40, CCL2). Ordinal logistic regressions were conducted to assess associations between cortisol patterns, neuroinflammation scores, and visual rating scales, and interactions between cortisol patterns and neuroinflammation composite scores in predicting visual rating scales.ResultHigher levels of angiogenesis markers were associated with greater odds of more severe white matter lesions. Furthermore, awakening cortisol levels, bedtime levels, CAR, and total daily output independently interacted with ‘other cytokines’ scores to predict MTA, CAR and total daily output independently interacted with ‘proinflammatory cytokines’ scores to predict white matter lesions, and the AM/PM ratio interacted with angiogenesis markers to predict GCA. No associations were found between cortisol patterns and visual rating scales.ConclusionThis study provides evidence for potential interplay between diurnal cortisol patterns and neuroinflammation. While this study does not provide information on causality, these findings suggest that neuroinflammation is involved in the pathway between chronic stress and AD.

Total Transfer Capacity Evaluation of HVDC Tie-Lines Considering Frequency Security Constraints

The high proportion of renewable energy access and the construction of HVDC transmission projects have led to a continuous decrease in the penetration rate of asynchronous power sources in the power system. Maintaining frequency stability and safe operation of the power system is a key issue that needs to be urgently addressed in the power grid. This article takes into account the participation of multiple types of power resources in inertia support and frequency modulation response and it also constructs an evaluation model for the total HVDC transfer capacity of the power grid. In response to the uncertainty of wind power and load power, scenario reduction methods are adopted to enhance the HVDC total transfer capacity of the power grid under frequency safety and stability constraints by the daily output of each power source. The simulation results indicate that the scheduling scheme evaluated by the proposed model has a higher frequency security level compared to traditional models.

A case study of a neighborhood in Douala examining the technical feasibility of a hybrid renewable energy system connected to the grid for energy and oxygen production in the fight against respiratory diseases

The world is increasingly focusing its attention on the rapid growth in electricity consumption, a concern shared by both industrialized and emerging nations. Meeting this escalating demand has become crucial, necessitating a shift towards sustainable energy use. Renewable energy sources have emerged as a popular choice for both off-grid and grid-connected installations as a means to bridge the efficiency gap. In this context, the present paper explores the potential of supplying electricity to a neighborhood in Cameroon comprising 100 homes through the integration of solar photovoltaic cells and electrolyzers. It is worth noting that Cameroon as a whole continues to grapple with severe social, economic, and physical challenges. Some regions within the country face significant obstacles in accessing quality healthcare, particularly for conditions like respiratory illnesses. This study employs an intelligent energy management method to design an optimal power flow control system, aimed at enhancing system stability during power outages and load fluctuations by effectively utilizing available storage capacity. The analysis was conducted using the Hybrid Optimization Model for Electric Renewable (HOMER) program. Our calculations reveal that a daily output of 0.123 kg mass of oxygen is produced, with renewable factor (RF) values indicating an 85.1 % integration of renewable sources, and the crucial parameter of Loss of Power Supply Probability (LPSP) reaching 0 %. These findings demonstrate that it is feasible for 100 homes to reliably generate and connect to the grid for electricity. Moreover, this research can serve as a solid foundation for the development of hybrid renewable energy systems to address the challenge of treating respiratory disorders such as COVID-19. These results underscore the significance of this study for various stakeholders, including decision-makers, policymakers, and investors in Cameroon and beyond. The ultimate goal is to promote national growth by improving socio-medical conditions.

Modes of North Atlantic Western boundary current variability at 36° N

The surface-intensified, poleward-flowing Gulf Stream (GS) encounters the equatorward-flowing Deep Western Boundary Current (DWBC) at 36° N off Cape Hatteras. In this study, daily output from a data-assimilative, high-resolution (800 m), regional ocean reanalysis was examined to quantify variability in the velocity structure of the GS and DWBC during 2017–2018. The validity of this reanalysis was confirmed with independent observations of ocean velocity and density that demonstrate a high level of realism in the model’s representation of the regional circulation. The model’s daily velocity time series across a transect off Cape Hatteras was examined using rotated Empirical Orthogonal Function analysis, and analysis suggests three leading modes that characterize the variability of the western boundary currents throughout the water column. The first mode, related to meandering of the GS current, accounts for 55.3% of the variance, followed by a “wind-forced mode”, which accounts for 12.5% of the variance. The third mode, influenced by the DWBC and upper-ocean eddies, accounts for 7.1% of the variance.

Effect of pretreatment with alkali on the anaerobic digestion characteristics of kitchen waste and analysis of microbial diversity

Abstract Kitchen waste contains high contents of organic matter and moisture, and it is prone to biodegrade and decompose to give odors. If not collected and transported promptly or treated improperly, it is highly likely to pollute the environment and spread diseases. Because the lipid content in kitchen waste is high and a portion of organic matter is not subject to hydrolysis, the development of anaerobic digestion technology has been greatly limited. Kitchen waste was pretreated with NaOH, KOH, and Ca(OH)2 with different concentrations, and 50 days sequencing batch mesophilic anaerobic digestion experiments were conducted. This study sheds light on the pollution reduction and energy generation of kitchen waste. The results are as follows: (1) The lipid content of kitchen waste could be reduced, and the concentration of dissolved organic matter could be increased by pretreating with alkali. The degradation rate of kitchen waste lipid reached a maximum of 50.51%, if 3% NaOH was added, and the soluble chemical oxygen demand concentration was increased by 235.3%. (2) The cumulative methane (CH4) output and biogas production efficiency were improved in the anaerobic digestion process with kitchen waste pretreated with alkali. The maximum daily gas output of kitchen waste pretreated with NaOH and KOH took place on the 11th to 12th day, with the biogas production efficiency of 40.4 and 45.2 mL·g·VS−1. The cumulative CH4 output was increased from 370.2 mL·g·VS−1 (untreated) to 393.1 and 434.1 mL·g·VS−1, respectively. In addition, the concentration of CH4 in biogas was increased from 54.8% (untreated) to 59.1% and 61.7%, respectively. (3) The Chao1 and Ace values of bacteria were increased first and then decreased. On the 10th day, the diversity of bacteria reached the highest value, and on the 20th day, the diversity of archaea reached its maximum. Therefore, it was verified that the improvement in the hydrolysis acidification efficiency and degree was crucial for the rapid and complete anaerobic digestion reactions.

Thermal Analysis of Single Slope Solar Still with Sensible Storage Material (Sand)

In this work authors utilized easily available and cheap sensible storage material (sand) in single basin solar still. The sensible storage material helps to enhance the distillate output from solar still during no sunshine hours. The mathematical model of the proposed solar still has been developed and experimentally validated. The numerical computation has been performed to analyse the effect of mass od sand placed beneath the basin plate. It is seen that with increase in mass of sand the overall daily distillate output decreases. When mass of sand increases from 15kg to 60 kg the daily distillate output decrease by 11.8%. The total daily distillate output produced by proposed still for a day in summer for Raipur is 5.32l/m2 which is about 24.4% more than conventional single slope solar still. The total nocturnal production of pure water from the propped still for a day in summer in Raipur climate is 1.37l/m2. The proposed solar still with sand storage is a good available cheap option to increase the overall productivity of conventional single slope solar still.

Feasibility study of crude oil mobilizing with nano emulsion in low oil saturation reservoir

The Chang 8 low oil saturation reservoir in Changqing Oilfield is highly heterogeneous and rich in organic matter, resulting in complex pore wettability. At present, when guar fracturing fluid is used for development, the wetting modification capacity of fracturing fluid is weak, the effect of imbibition on enhancing oil recovery (EOR) is poor, and the mobilization ratio of large pores oil is only 5.40%, and the total recovery rate in lab is less than 25%. There is an urgent need for a highly efficient oil mobilization reagent with strong modification capacity and capable of simultaneously mobilization core micro and nano-pore crude oil. Through relative permeability displacement and forced imbibition, it is found that the residual oil saturation of core is 29.87%. However, the oil saturation range of Chang 8 reservoir is only 12.2%–33.2%, and it is the main reason for the difficulty in mobilizing crude oil. Then, based on different types of chemical reagents, 0.10% KX-7 oil mobilization reagent is optimized through the nuclear magnetic resonance (NMR) method. The particle size of 0.10% KX-7 nano emulsion is about 10 nm, the imbibition recovery rate is 44.24%, and the mobilization ratio of small pores (nano-scale) and large pores (micro-scale) is 45.52% and 35.73% respectively, and the wettability angle of core is modified to 44°, which can reduce the residual oil saturation of the core to 18.20%. Its main mobilization mechanism is wetting modification and solubilization. Increasing reagent concentration, temperature, and pressure can promote the mobilization and modification capacity of KX-7 nano emulsion, and the mobilization ratio of crude oil is further increased by more than 10%. The optimized KX-7 nano emulsion has a good performance in the field test with a daily output of 28.2 tons, which can guide the highly efficient development of low oil saturation reservoirs.

Benefits of Preserving Residual Urine Output in Patients Undergoing Maintenance Haemodialysis.

Chronic kidney disease is a widespread medical problem that leads to higher morbidity, mortality, and a decrease in the overall well-being of the general population. This is especially expressed in patients with end-stage renal disease (ESRD) undergoing maintenance haemodialysis. Several variables could be used to evaluate those patients' well-being and mortality risk. One of them is the presence of residual urine output. The study was conducted on 485 patients treated with maintenance haemodialysis. After enrollment in the study, which consisted of medical history, physical examination, hydration assessment, and blood sampling, each patient was followed up for 24 months. We used residual urine output (RUO) as a measure of residual renal function (RRF). The entire cohort was divided into 4 subgroups based on the daily urinary output (<=100mL per day, >100mL to <=500mL, >500mL to <=1000mL and >1000mL). The data show that the mortality rate was significantly higher in groups with lower RUO, which was caused mainly by cardiovascular events. Also, patients with higher RUO achieved better sodium, potassium, calcium, and phosphate balance. They were also less prone to overhydration and had a better nutritional status. Preserved RRF also had a positive impact on markers of cardiovascular damage, such as NT-proBNP as well as TnT. In conclusion, preserving residual urine output in ESRD patients undergoing maintenance haemodialysis is invaluable in reducing their morbidity and mortality rates and enhancing other favourable parameters of those patients.

First-Year Experience of IMRT/SBRT Treatments Using a Novel Biology-Guided Radiation Therapy System

This study presents the first-year experience of treating patients using intensity-modulated radiation therapy (IMRT) and stereotactic body radiation therapy (SBRT) with the X1 system, the first biology-guided radiation therapy (BgRT) machine installed in a clinical setting. A total of 78 patients underwent IMRT and SBRT treatments on the X1 system from May 2021 to May 2022. Clinical and technical data, such as treatment sites, number of pre-treatments kVCT scans, beam on time, patient setup time, imaging time per kVCT, and couch shifts after kVCT match, were collected and analyzed. Additionally, daily machine output stability, patient-specific quality assurance (QA) results, machine uptime, and user survey were also documented and reported. The most commonly treated site was the head and neck (63%), followed by the pelvis (23%), thorax (6%), and abdomen (8%). All treatments, except for 5 pelvis patients (6%) who received SBRT treatments for bony metastases, were conventionally fractionated IMRT (CF IMRT). The average number of kVCT scans per fraction is 1.2 ± 0.5 for all treatments. The average beam on time in minutes was 9.2 ± 3.5 for all treatments, 8.4 ± 2.4 for head and neck, 6.7 ± 1.3 for thorax, 10.3 ± 1.6 for abdomen, 11.6 ± 5.1 for CF IMRT pelvis, and 10.8 ± 5.3 for SBRT pelvis. The average patient setup time and imaging time per kVCT was 4.8 ± 2.6 minutes and 4.6 ± 1.5 minutes, respectively. The average couch corrections based on kVCT images were 0.4 ± 4.4 mm, 1.0 ± 4.5 mm, and 1.3 ± 4.3 mm along the x, y, and z direction, respectively; the average couch rotation corrections were 0.1 ± 0.9° for pitch, 0.0 ± 0.9° for roll, and 0.2 ± 1.2° for yaw. The daily machine output was 0.4 ± 1.2% from the baseline. The patient QA had a gamma passing rate of 97.4 ± 2.8%. The machine uptime was 92% of the total treatment time. The kVCT image quality and daily QA process received the highest level of satisfaction, while the treatment workflow for therapists received the lowest level of satisfaction (table 1). At one year after the installation of the X1 system, this study reports successful treatment of 78 patients using IMRT/ SBRT. With the recent FDA clearance of BgRT, our institution is preparing to treat patients using PET-guidance via a new product release, which should address deficiencies in the current IGRT workflow.

Monte Carlo simulation-based patient-specific QA using machine log files for line-scanning proton radiation therapy.

Quality assurance (QA) is a prerequisite for safe and accurate pencil-beam proton therapy. Conventional measurement-based patient-specific QA (pQA) can only verify limited aspects of patient treatment and is labor-intensive. Thus, a better method is needed to ensure the integrity of the treatment plan. Line scanning, which involves continuous and rapid delivery of pencil beams, is a state-of-the-art proton therapy technique. Machine performance in delivering scanning protons is dependent on the complexity of the beam modulations. Moreover, it contributes to patient treatment accuracy. A Monte Carlo (MC) simulation-based QA method that reflects the uncertainty related to the machine during scanning beam delivery was developed and verified for clinical applications to pQA. Herein, a tool for particle simulation (TOPAS) for nozzle modeling was used, and the code was commissioned against the measurements. To acquire the beam delivery uncertainty for each plan, patient plans were delivered. Furthermore, log files recorded every 60 μs by the monitors downstream of the nozzle were exported from the treatment control system. The spot positions and monitor unit (MU) counts in the log files were converted to dipole magnet strengths and number of particles, respectively, and entered into the TOPAS. For the 68 clinical cases, MC simulations were performed in a solid water phantom, and two-dimensional (2D) absolute dose distributions at 20-mm depth were measured using an ionization chamber array (Octavius 1500, PTW, Freiburg, Germany). Consequently, the MC-simulated 2D dose distributions were compared with the measured data, and the dose distributions in the pre-treatment QA plan created with RayStation (RaySearch Laboratories, Stockholm, Sweden). Absolute dose comparisons were made using gamma analysis with 3%/3mm and 2%/2mm criteria for 47 clinical cases without considering daily machine output variation in the MC simulation and 21 cases with daily output variation, respectively. All cases were analyzed with 90% or 95% of passing rate thresholds. For 47 clinical cases not considering daily output variations, the absolute gamma passing rates compared with the pre-treatment QA plan were 99.71% and 96.97%, and the standard deviations (SD) were 0.70% and 3.78% with the 3%/3mm or 2%/2mm criteria, respectively. Compared with the measurements, the passing rate of 2%/2mm gamma criterion was 96.76% with 3.99% of SD. For the 21 clinical cases compared with pre-treatment QA plan data and measurements considering daily output variations, the 2%/2mm absolute gamma analysis result was 98.52% with 1.43% of SD and 97.67% with 2.72% of SD, respectively. With a 95% passing rate threshold of 2%/2mm criterion, the false-positive and false-negative were 21.8% and 8.3% for without and with considering output variation, respectively. With a 90% threshold, the false-positive and false-negative reduced to 11.4% and 0% for without and with considering output variation, respectively. A log-file-based MC simulation method for patient QA of line-scanning proton therapy was successfully developed. The proposed method exhibited clinically acceptable accuracy, thereby exhibiting a potential to replace the measurement-based dosimetry QA method with a 90% gamma passing rate threshold when applying the 2%/2mm criterion.