A new state-observer-based current balancing method for Modular Multilevel Converters with Interleaved half-bridge Sub-Modules (ISM-MMC) is presented in this article. The developed observer allows ...estimating currents through interleaved half-bridge legs in each submodule of ISM-MMC based only on arm current and submodule's capacitor voltage measurements. Then, the interleaved current balancing control uses the estimated currents to reduce the interleaved currents imbalance caused by upstream control actions. This technique minimizes the number of required current sensors in ISM-MMC, thereby reducing the converter's cost, weight, and volume. Capabilities of the proposed sensorless interleaved currents balancing control have been tested against standard parameter tolerances of the composing passive elements. In addition to that, a novel capacitor voltage balancing strategy for MMCs is developed. The new algorithm contains the main advantages of the classical sorting-based capacitor voltage balancing methods while providing an opportunity to decouple two balancing tasks of ISM-MMC, namely capacitor voltage and interleaved legs current balancing. The feasibility of the proposed methods is verified by extensive simulation and experimental tests on a laboratory prototype by the corresponding system response under the output characteristics variation and interleaved current control perturbation.
•The optimal activation of balancing resources reduces the costs for balancing energy.•The transmission network constraints should be considered in regional balancing.•The regional integration of ...balancing markets reduces the balancing costs.•The increased RES penetration increases the need for balancing energy.
The objective of this paper is to introduce an approach for enabling optimal activation of balancing energy resources within a regional balancing market. In order to take into account the constraints from the transmission network, the paper proposes a modified technique for optimal power flow calculation. This novel approach results in a more effective usage of transmission network capacities during reserve activation on a regional level compared to the conventional Common Merit Order List (CMOL) approach, which only considers the available cross-zonal transmission capacity (CZC) and disregards the physical power flows. The paper provides details on a procedure that includes simulation of electricity markets, as well as simulation on imbalances in the system. The methodology is used for evaluating the proposed approach on an IEEE test system comprising of three zones. The paper shows a significant reduction of balancing costs by implementation of regional balancing market it also investigates and shows the impact of the increased RES penetration to the amount of needed balancing energy in the system.
Given a finite set of jobs and a common resource. Each job has the same processing time p, alongside an individual release date and deadline, and utilizes either zero or one unit from the resource. A ...schedule specifies a star time for each job, and it determines the resource usage over time. The objective is to minimize a separable convex function of the resource usage. Prior to our work, the existing body of research only tackled the scenario where p=1. We explore three variations of this fundamental problem, accompanied by applications drawn from existing literature. In the first variant, all jobs require one unit of the resource each. In the second and third variants, there are m parallel machines, and at most m jobs may be processed concurrently at any given moment. Furthermore, in the second variant, each job has a unit processing time, and may require either 0 or 1 unit of the resource. In the third case, there are ν distinct resource types each linked with a convex function, and each job requires precisely one of these resources types. The jobs have a uniform processing time p and possess agreeable release dates and deadlines. For each of these cases, we introduce novel polynomial-time algorithms designed to determine optimal solutions.
•Scheduling of equal processing time jobs with release dates and deadlines.•Jobs require one unit from the same resource, or one unit from one resource from a given set of resources.•The cost of resource usage is determined by a separable convex function.•The objective is to minimize the total resource usage cost.•Polynomial time algorithms are devised for a couple of variants of the problem.
Thanks to new technological advancements and EU policy impulse, distributed energy resources (DER) are poised to become a viable alternative to conventional electricity generation for the provision ...of balancing services to transmission system operators. In this paper we show that the design variables that affect DER access to and participation in the organized balancing market include different features of auction configuration as well as a number of formal, administrative and technical aspects of market design. In a comparative case study of the balancing markets in Austria, Germany and the Netherlands, we determine the extent to which a given market design effectively facilitates DER participation. To structure this analysis, we designed an assessment framework that provides a comprehensive tool for the assessment of balancing markets in Europe vis-à-vis DER participation. Our results show that flexible pooling conditions, a higher bidding frequency and product resolution, and the authorization of non-precontracted bids, among others, can significantly ease DER integration in the market. Different design variables, however, can enhance or neutralize each other's effects, so their interrelations need to be taken into account in order to achieve an improved and harmonized balancing market design.
•Distributed energy resources (DER) can provide cost-efficient balancing services.•Current European balancing markets do not sufficiently facilitate entry of DER.•European balancing market designs are highly heterogeneous.•Assessment framework helps to reveal ways to incentivize DER participation in balancing markets.•Key opportunities for improvement to balancing market design have been identified.
As both CPUs and GPUs become employed in a wide range of applications, it has been acknowledged that both of these Processing Units (PUs) have their unique features and strengths and hence, CPU-GPU ...collaboration is inevitable to achieve high-performance computing. This has motivated a significant amount of research on heterogeneous computing techniques, along with the design of CPU-GPU fused chips and petascale heterogeneous supercomputers. In this article, we survey Heterogeneous Computing Techniques (HCTs) such as workload partitioning that enable utilizing both CPUs and GPUs to improve performance and/or energy efficiency. We review heterogeneous computing approaches at runtime, algorithm, programming, compiler, and application levels. Further, we review both discrete and fused CPU-GPU systems and discuss benchmark suites designed for evaluating Heterogeneous Computing Systems (HCSs). We believe that this article will provide insights into the workings and scope of applications of HCTs to researchers and motivate them to further harness the computational powers of CPUs and GPUs to achieve the goal of exascale performance.
Line balancing is always a big problem appearing in industrial production. Manual balancing of industrial sewing products takes a long time to give results, which depends on the experience of the ...sewing line manager, moreover, the efficiency is not necessarily optimal. Digital conversion will help find a solution to balance the sewing line more quickly, accurately, and optimally. This study presents the statements of the problem of balancing knitted garment lines in the industry with the line balancing process according to the method of Hanoi University of Science and Technology (HUST) and BSL-HUST-1 software, which is the software designed and built by our research group. For the balancing calculation, three groups of input data were defined for the comparison of balancing efficiency among the HUST method, the software method, and the method used traditionally by the companies. The line's capacity is determined as the total production amount in a shift, and the shift time is figured accordingly following each factory's rules. The total number of workers is an essential factor. Also, the cycle time is one of the important factors for balancing the sewing line.
A study of the k-step generalized balancing sequences Cetinalp, E.K.; Deveci, O.; Yilmaz, N.
Bulletin of the Transilvania University of Brasov. Series III: Mathematics and Computer Science,
07/2023
Journal Article
In this paper, firstly, we define the k-step generalized Balancing sequences and study the Binet formula of these sequences. Also, we find families of super-diagonal matrices such that the permanents ...of these matrices are the elements of the k-step generalized Balancing sequences. Finally, we examine the periods of the k-step Balancing sequences in the semi-direct product presented by G = < x, y | x2m−1 = y2 = 1, yxy = x−1 > for the generating pair (x, y).
The manufacturing industry has been pursuing an efficient and economical assembly system. By considering assembly line balancing (ALB) and part feeding (PF) as an integrated problem and programming ...them simultaneously opens additional opportunities to improve the performance of the entire assembly system. However, the integrated ALB and PF problem is a non-deterministic polynomial (NP) hard problem. This implies that exact solutions cannot be obtained in a reasonable computation time and its near-optimal solutions can only be realised by meta-heuristics. In this study, we propose a novel bi-level multi-objective genetic algorithm (NBMGA) to solve the integrated ALB and PF problem. First, a bi-level mathematical model is established to simultaneously minimise the number of stations and workload smoothness of ALB in the upper level as well as the number of supermarkets of PF in the lower level. Second, the NBMGA with two modified strategies, including extending fitness evaluation and adaptive termination condition, is designed for problem solving. Finally, a series of computational experiments are conducted to demonstrate the efficacy of the proposed algorithm. The computational results indicate that the proposed algorithm outperforms the bi-level nondominated sorting genetic algorithm (NSGA) II in terms of the approximation to the true frontier without sacrificing computational efficiency.
The input-parallel output-parallel (IPOP) connected converter system allows the use of a low-power converter module for high-power applications. However, mismatches in the IPOP circuit parameters ...cause uneven current sharing between the constituent modules, which makes the IPOP system unreliable for practical use. Different techniques have been proposed so far; however, they cause an increase in magnetic volume, cost, component count, and complexity of the IPOP system. In this article, a reliable and efficient magnetic integration technique is proposed for the current sharing requirements of the IPOP system based on LLC resonant converter modules. The proposed integrated magnetic current balancing transformer (ICBT) based IPOP LLC resonant converter modules ensures both the input current sharing and output current sharing between constituent LLC modules, under the open-loop condition quite effectively. The proposed ICBT is the resonant inductors of LLC resonant converter modules, coupled to perform the function of current balancing as well as generates enough leakage inductances for resonance operation, simultaneously. Thus, it can reduce the overall magnetic volume and improves power density of the IPOP LLC modules. Moreover, the current sharing performances of the proposed ICBT in both the steady-state and dynamic-state are analyzed based on the magnetic and electrical model. To validate the performance of the proposed ICBT based IPOP two LLC modules, a 2.6-kW hardware prototype was designed, fabricated, and tested successfully.
This systematic review and meta-analysis were conducted to compare the accuracy of component positioning, alignment and balancing techniques employed, patient-reported outcomes, and complications of ...robotic-arm assisted total knee arthroplasty (RATKA) with manual TKA (mTKA) and the associated learning curve. Searches of PubMed, Medline and Google Scholar were performed in October 2020 using PRISMA guidelines. Search terms included “robotic”, “knee” and “arthroplasty”. The criteria for inclusion were published clinical research articles reporting the learning curve for RATKA and those comparing the component position accuracy, alignment and balancing techniques, functional outcomes, or complications with mTKA. There were 198 articles identified, following full text screening, 16 studies satisfied the inclusion criteria and reported the learning curve of rTKA (
n
=5), component positioning accuracy (
n
=6), alignment and balancing techniques (
n
=7), functional outcomes (
n
=7), or complications (
n
=5). Two studies reported the learning curve using CUSUM analysis to establish an inflexion point for proficiency which ranged from 7 to 11 cases and there was no learning curve for component positioning accuracy. The meta-analysis showed a significantly lower difference between planned component position and implanted component position, and the spread was narrower for RATKA compared with the mTKA group (Femur coronal: mean 1.31, 95% confidence interval (CI) 1.08–1.55,
p
<0.00001; Tibia coronal: mean 1.56, 95% CI 1.32–1.81,
p
<0.00001). Three studies reported using different alignment and balancing techniques between mTKA and RATKA, two studies used the same for both group and two studies did not state the methods used in their RATKA groups. RATKA resulted in better Knee Society Score compared to mTKA in the short-to-mid-term follow up (95%CI − 1.23, − 0.51,
p
=0.004). There was no difference in arthrofibrosis, superficial and deep infection, wound dehiscence, or overall complication rates. RATKA demonstrated improved accuracy of component positioning and patient-reported outcomes. The learning curve of RATKA for operating time was between 7 and 11 cases. Future well-powered studies on RATKAs should report on the knee alignment and balancing techniques utilised to enable better comparisons on which techniques maximise patient outcomes.
Level of evidence
III.
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