Zone Partitioning Research Articles

A MILP-based power system parallel restoration model with the support of mobile energy storage systems

During bulk power system restoration, black-start (BS) units are used to crank non-BS units in such a way that the over system generation capability is maximized. However, traditional power system restoration methods rely on stationary BS units, whose number is limited due to high investment and geographic conditions, impeding a fast system restoration. To enhance restoration efficiency, this paper proposes an integrated power system parallel restoration method considering the support of mobile energy storage systems (MESSs), which can provide cranking power to non-BS units and transform them into MESS-assisted BS units. MESSs are routed and scheduled via transportation network, along with restoration planning in power network by integrating them into a mixed integrated linear programming model. Specifically, to describe the interactive behavior between MESSs and the power system, a mobility model for MESSs is proposed, which indicates the travel path, travel time and connection nodes. Then, an integrated optimization model involving BS unit location, zone partitioning, network reconfiguration and generator start-up is formulated. The proposed method was simulated in the modified IEEE 30-bus transmission system coupled with 11-node transportation system. The results show that, in contrast with a decoupled restoration method, the proposed method increases system generation capability by 6.3%.

Longitude-based time zone partitions and rates of suicide

BackgroundIncreasing evidence suggests that conditions with decreased morning and increased evening light exposure, including shift work, daylight-saving time, and eveningness, are associated with elevated mortality and suicide risk. Given that the alignment between the astronomical, biological, and social time varies across a time zone, with later-shifted daylight exposure in the western partition, we hypothesized that western time zone partitions would have higher suicide rates than eastern partitions. MethodsUnited States (U.S.) county-level suicide and demographic data, from 2010 to 2018, were obtained from a Centers for Disease Control database. Using longitude and latitude, counties were sorted into the western, middle, or eastern partition of their respective time zones, as well as the northern and southern halves of the U.S. Linear regressions were used to estimate the associations between suicide rates and time zone partitions, adjusting for gender, race, ethnicity, age group, and unemployment rates. ResultsData were available for 2872 counties. Across the U.S., western partitions had statistically significantly higher rates of suicide compared to eastern partitions and averaged up to two additional yearly deaths per 100,000 people (p < .001). LimitationsEcological design and limited adjustment for socioeconomic factors. ConclusionsTo our knowledge, this is the first study of the relationship between longitude-based time zone partitions and suicide. The results were consistent with the hypothesized elevated suicide rates in the western partitions, and concordant with previous reports on cancer mortality and transportation fatalities. The next step is to retest the hypothesis with individual-level data, accounting for latitude, photoperiodic changes, daylight-saving time, geoclimatic variables, physical and mental health indicators, as well as socioeconomic adversity and protection.

Passenger spatiotemporal distribution prediction in airport terminals based on insect intelligent building architecture and its contribution to fresh air energy saving

As the essential infrastructure and important transportation hubs, airport terminals play a strategic role in sustainable cities and urbanization. Due to the strict service requirement and round-the-clock operation, the high energy consumption poses unprecedented challenges to developing environment-friendly airport terminals. Actually, passenger flow as a root cause decides the startup and operation of service facilities including air-conditioning systems. But due to spatial connectivity, parameter coupling, and passenger mobility, resource allocation and system tuning have not been effectively related to passenger travel. In this work, Guangzhou Baiyun International Airport Terminal 2 was taken as an object, and a passenger spatiotemporal distribution model was developed and its contribution to fresh air energy saving was estimated. Among them, zone partition and expression rules were formulated based on insect intelligent building (I2B) architecture to construct Wi-Fi positioning system; Next, for domestic and international passenger, their arrival patterns were fitted by Chi-Square distribution with R2 > 0.993, and their spatiotemporal distribution was predicted with R2 over 0.74 and 0.67 respectively; Lastly, a hybrid reset strategy for fresh air volume set-point combing fuzzy and linear rules was proposed with results showing that HVAC systems running on variable occupancy would lead to considerable energy savings.

The anatomic zone localization based on biparametric MRI for the prediction of the risk degree of prostate cancer

Objective: To investigate the anatomic zone localization based on biparametric magnetic resonance imaging (bpMRI) for the prediction of the risk degree in patients with prostate cancer. Methods: A total of 92 patients with prostate cancer confirmed by radical surgery in First Affiliated Hospital, Air Force Medical University, from January 2017 to December 2021 were collected. All patients underwent bpMRI (non-enhanced scan and DWI). According to ISUP grade, those patients were divided into low-risk group [≤grade 2, n=26, aged 71 (64.0, 5.2) years] and high-risk group[≥grade 3, n=66, aged 70.5 (63.0, 74.0) years]. The interobserver consistency test for ADC values was evaluated using the intraclass correlation coefficients (ICC). The differences in total prostate specific antigen (tPSA) between the two groups were compared and the χ2 test was used to compare the differences in the risk of prostate cancer in the transitional and peripheral zone. Independent correlation factors for prostate cancer risk were analyzed by logistic regression using high and low risk of prostate cancer as dependent variables, including factors such as anatomical zone, tPSA, apparent diffusion coefficient mean (ADCmean), apparent diffusion coefficient minimum (ADCmin) and age. Receiver operating characteristic (ROC) curves were plotted to assess the efficacy of the combined models of anatomical zone, tPSA, and anatomical partitioning+tPSA for diagnosing prostate cancer risk. Results: The ICC values of the ADCmean and ADCmin between the observers were 0.906 and 0.885, respectively, with good agreement. The tPSA in the low-risk group was lower than that in the high-risk group [19.64 (10.29, 35.18) ng/ml vs 72.42 (24.79, 187.98) ng/ml; P<0.001]; the risk of prostate cancer in the peripheral zone was higher than that in the transitional zone, and the difference was statistically significant (P<0.01). Multifactorial regression showed that anatomical zones (OR=0.120, 95%CI:0.029-0.501, P=0.004) and tPSA (OR=1.059, 95%CI:1.022-1.099, P=0.002) were risk factors for prostate cancer risk. The diagnostic efficacy of the combined model (AUC=0.895, 95%CI: 0.831-0.958) was better than the predictive efficacy of the single model for both anatomical partitioning (AUC=0.717, 95%CI:0.597-0.837) and tPSA (AUC=0.801, 95%CI: 0.714-0.887) (Z=3.91, 2.47; all P<0.05). Conclusions: The malignant degree of prostate cancer in peripheral zone was higher than that in transitional zone. Combination of anatomic zone located by bpMRI and tPSA can be used to predict the risk of prostate cancer before surgery, expected to provide support for patients to develop personalized treatment strategies.

Comparing air sealing techniques for suite compartmentalization in a multi-unit residential building: Aerosolized sealant vs. conventional air sealing approaches

Recently, the use of aerosolized sealant has been proposed as an alternative to conventional (manual) air sealing approaches for suite compartmentalization in multi-unit residential buildings (MURBs). With this approach, aerosolized sealant is released into a positively pressurized zone; the resulting pressure differential across the zone partition draws the aerosolized product to the leakage paths where the particles accumulate until the leakage path is fully sealed. In theory, aerosolized sealants are more effective than conventional air sealing, as their installation does not require manual identification of leakage pathways. However, prior studies assessing the efficacy of aerosolized sealants have typically not included control groups, making it difficult to quantitatively compare aerosolized sealants against conventional techniques. This paper compares the performance of conventional air sealing approaches against aerosolized sealant (for suite compartmentalization) in a newly constructed MURB, in Toronto, Canada. Compartmentalization was assessed using unguarded, suite-level blower door tests. On average, suites sealed using aerosolized sealant were 27% tighter than those sealed using conventional approaches (q50 = 0.22L/s/m2 of suite surface area (0.04cfm50/ft2) vs. 0.30L/s/m2 (0.06cfm50/ft2), N = 5 suites per test group) – a statistically significant difference (t(8) = -2.01, p = 0.04). Guarded floor-level air leakage testing revealed that aerosolized sealant was most effective for leakage paths on vertical surfaces and had no impact on floor/ceiling airtightness. Apart from quantitative system performance, this paper discusses advantages and disadvantages of aerosolized sealants, based on lessons learned from the case study building. These results can help building designers and contractors weigh the relative benefits of using aerosolized sealants for suite compartmentalization.

Frequency selection method for urban low frequency multi‐terminal interconnected systems

AbstractLarge‐scale urban power grid (LUPG) is normally under the operating mode by voltage layer and zone partition. One of the most important directions for the development of urban is to enhance the controllability by flexible low‐frequency interconnection technology. In this study, a frequency selection method for urban low‐frequency multi‐terminal interconnected systems (ULFMIS) is proposed. Firstly, the required support power under different conditions, the index number of sending partition (SP) and receiving partition (RP) are determined. Secondly, by calculating the current distribution along the line under different support powers, the upper limit of the transmission frequency (ULTF) of each line is obtained. Finally, the smallest transmission frequency among the ULTFs of different tie lines is selected as the ULTF of the ULFMIS. The proposed method is validated in a typical four‐terminal ULFMIS. The results demonstrate that the suggested method is suitable for calculating the ULTF taking account of the influence of the number of parallel lines on economic cost and provide guidance for future practical ULFMIS projects.

Bi-Level Coordinated Power System Restoration Model Considering the Support of Multiple Flexible Resources

When power systems encounter outages and large-scale blackouts, system restoration is critical and should be carried out with dedicated schemes. In this past, most studies divided the power system restoration into three stages (i.e., black-start zone partitioning, network reconfiguration, and load restoration) and deal with them separately. After that, few studies considering the three stages together were emerging while the support of multiple flexible resources, i.e., renewable energy source (RES), electric vehicle system (EVS) and energy storage system (ESS), were not considered comprehensively. Therefore, a bi-level coordinated power system restoration (BiCPSR) model is proposed in this work considering the support of multiple flexible resources. In the upper level, two network topology indices that describe the “reachability” and “shortest reachable distance” of buses in power systems, and the restoration characteristics of generators and loads are utilized for optimizing the start-up sequence of generators and network reconfiguration. In the lower level, the uncertainties of RES and EVS are considered by various scenarios and the support of multiple flexible resources is utilized cooperatively for accelerating the restoration process and maximizing the restorable load. Case studies on the revised IEEE 39-bus, WECC 179-bus and the actual Zhejiang power systems are performed to illustrate the basic features of the proposed model and its availability in bulk power systems. The comparisons between the proposed model and other models are also performed to illustrate the strengths of the proposed model.

Bi-Level Fleet Dispatching Strategy for Battery-Electric Trucks: A Real-World Case Study

Driven by new regulations concerning greenhouse gas (GHG) emissions in the transportation sector, battery-electric trucks (BETs) are considered one of the sustainable freight transportation solutions. In this paper, a dispatching problem of the BET fleet is formulated as a capacitated electric vehicle routing problem (VRP) with pick-up and delivery. As the BET dispatching problem is NP-hard, the performance of existing approaches deteriorates in large instance problems, especially when the customers have different preferences and constraints. This article proposes a bi-level strategy that incorporates routing zone partitioning and metaheuristic-based vehicle routing to solve the large-scale BET dispatching problem, considering the delivery types, limited travel distances, and cargo payloads. We apply this strategy to a real-world fleet dispatching scenario with around 300 customer positions for pickups and drop-offs. The experimental results demonstrate that the proposed bi-level strategy can reduce total travel distance and travel time by 24–31%, compared to the baseline strategy implemented in the real world.

A novel zone-based machine learning approach for the prediction of the performance of industrial flares

Industrial flares are used to burn off unwanted gas during operation. If not combusted completely, intermediate products or incomplete combustion products are formed, and they will cause significant environmental and health issues. The EPA Refinery Sector Rule emphasizes smokeless flaring with combustion efficiency (CE) ≥ 96.5% and destruction and removal efficiency (DRE) ≥ 98% for all types of flares in the refineries. In this research, a novel zone-based modeling approach was developed for predicting CE and Opacity of steam assist flares. Flare CE data were partitioned into two zones based on the partition of the carbon and hydrogen atomic ratio (CHR), then random forest (RF) and Catboost algorithms were used to develop CE predictive models, respectively. This CHR-based zone partition has a clear implication in engineering. It was also found out that no zone division for flare Opacity prediction is needed, and both RF and Catboost algorithms generated good prediction results. All the models match extremely well with all the original experimental data. These predictive models under the same zone-partition use either RF or Catboost algorithm can both give superior prediction accuracy. This demonstrates the simplicity, general applicability, and high reliability of the zone-based ML approach.

Analysis of four shield-driven tunnels with complex spatial relations in a clay stratum

The tunnelling-induced ground settlement is a key concern during urban underground construction. This paper examined the ground settlement caused by multi-line tunnelling with earth pressure balance shield in the clay stratum in Tianjin, China. Laboratory tests are conducted to determine the soil parameters used in the modified Cam-Clay model. The real-data numerical simulation achieves a good agreement with in-situ monitoring data. The influence zone partition of multi-line tunnel construction is obtained and then used to evaluate the safety risks. An improved Peck formula is proposed based on the combination of superposition, overlapping and grouting effects. The parameter ranges are calibrated by means of statistical and numerical analysis. This study provides a reliable reference and practical tool for design and construction of multiple tunnels in a clay stratum.

Core physical conceptual design of small reactor for unmanned underwater vehicle

In order to improve the endurance of unmanned underwater vehicle (UUV) and meet the needs of long-term underwater mission, the conceptual design of the 3.68 MWt long-life small reactor JCZER-20 is carried out in an UUV application scenario with a propulsive power of 850 kW. According to the design content, the concept of active zone partition design is put forward, and a new circulating scheme of coolant in the reactor primary circuit is given. The layout of control body in the reactor and the design of control system are carried out. The control rod structure of JCZER-20 adopts special design to deal with special conditions such as shaking during operation. The reactivity distribution scheme is given, and the reactor physical characteristics are analyzed for the design scheme. This scheme can lengthen coolant channels, effectively improve the total temperature rise of the coolant, but not increase the extra heat load. MCNP-ORIGEN2 simulation results show that the JCZER-20 reactor can operate at full power for more than 30 years without refueling. The reactor core reactivity can be effectively controlled by the control system of reactor. The core design meets preset design requirements.

Anti-rollover Control of Counterbalanced Forklift Truck Based on Stable Zone Partition

Anti-rollover Control of Counterbalanced Forklift Truck Based on Stable Zone Partition

Procedure for Estimating Bending and Torsional Fatigue Strength of Smooth Specimens on Criteria of Axial-Load Fatigue Strength Diagrams

The equivalent cyclic stress ratio REQ followed by elastic-completely plastic yield zone partition type cross-section dimension dependence magnification factor, which is modified to fatigue strength criterion specification, is applied to estimation of plane bending fatigue strength of a smooth bar with rectangular, circular and rhombic cross-section, and rotating bending and torsion fatigue strength of a round smooth bar from an axial load fatigue strength diagram of a smooth specimen. This approach is expected to be effective in elucidating the size effect and its material dependence.

Anti-Rollover Control Based on Stable Zone Partition of Counterbalanced Forklift Trucks

Anti-Rollover Control Based on Stable Zone Partition of Counterbalanced Forklift Trucks

Power System Zone Partitioning Based on Transmission Congestion Identification Using an Improved Spectral Clustering Algorithm

The ever-expanding power system is developed into an interconnected pattern of power grids. Zone partitioning is an essential technique for the operation and management of such an interconnected power system. Owing to the transmission capacity limitation, transmission congestion may occur with a regional influence on power system. If transmission congestion is considered when the system is decomposed into several regions, the power consumption structure can be optimized and power system planning can be more reasonable. At the same time, power resources can be properly allocated and system safety can be improved. In this paper, we propose a power system zone partitioning method where the potential congested branches are identified and the spectral clustering algorithm is improved. We transform the zone partitioning problem into a graph segmentation problem by constructing an undirected weighted graph of power system where the similarities between buses are measured by the power transfer distribution factor (PTDF) corresponding to the potential congested branches. Zone partitioning results show that the locational marginal price (LMP) in the same zone is similar, which can represent regional price signals and provide regional auxiliary decisions.

Optimal Partitioning of Multithermal Zone Buildings for Decentralized Control

In this article, we used an optimization-based systematic methodology for the challenging, less studied, and important problem of optimal partitioning of multithermal zone buildings for decentralized control. The proposed methodology consists of: i) construction of a graph-based network to quantitatively characterize the thermal interaction levels between neighboring zones and ii) the application of two different approaches for optimal clustering of the resulting network graph: 1) stochastic optimization and 2) robust optimization. The proposed optimization methods were tested and compared with each other on two case studies: 1) a five-zone building (a small-scale example) which allows one to consider all possible partitions to assess the success rate of the developed methods and 2) a 20-zone building (a large-scale example) for which the developed methods were used to predict the optimal partitioning of the thermal zones. Compared to the existing literature, our approach provides a systematic and potentially optimal solution for the considered problem.

An innovative machine learning based framework for water distribution network leakage detection and localization

Leakages in the underground water distribution networks (WDNs) waste over 1 billion gallon of water annually in the US and cause significant socio-economic loss to our communities. However, detecting and localization leakage in a WDN remains a challenging technical problem despite of significant progresses in this domain. The progresses in machine learning (ML) provides new ways to identify the leakage by data-driven methods. However, in-service WDNs are short of labeled data under leaking conditions, which makes it infeasible to use common ML models. This study proposed a novel machine learning (ML)-based framework for WDN leak detection and localization. This new framework, named clustering-then-localization semi-supervised learning (CtL-SSL), uses the topological relationship of WDN and its leakage characteristics for WDN partition and sensors placement, and subsequently utilizes the monitoring data for leakage detection and leakage localization. The CtL-SSL framework is applied to two testbed WDNs and achieves 95% leakage detection accuracy and around 83% final leakage localization accuracy by use of unbalanced data with less than 10% leaking data. The developed CtL-SSL framework advances the leak detection strategy by alleviating the data requirements, guiding optimal sensor placement, and locating leakage via WDN leakage zone partition. It features excellent scalability, extensibility, and upgradeability for applications to various types of WDNs. It will provide valuable a tool in sustainable management of the WDNs.

An ultra-efficient design and optimized energy dissipation of reversible computing circuits in QCA technology using zone partitioning method

An ultra-efficient design and optimized energy dissipation of reversible computing circuits in QCA technology using zone partitioning method

Mobility service design via joint optimization of transit networks and demand-responsive services

This paper proposes a modeling framework to design an integrated mobility service system that is composed of a local demand-responsive transportation (DRT) component and a fixed-route transit network component. The region is partitioned into disjoint local zones, and a trip is characterized into an intra- or inter-zonal one based on whether its origin and destination belong to the same zone. The transit network provides backbone line-haul service to inter-zonal trips, while the DRT system targets intra-zonal trips as well as the first-mile and last-mile legs of inter-zonal trips. The system components can be broadly defined, and this paper considers, as examples, conventional non-shared taxi or ride-sharing for the DRT service, and regular bus, bus rapid transit (BRT), or metro for the backbone network. For quantitative analysis of the DRT services, new aspatial queuing network models are developed to capture various DRT operations for serving trips with randomly distributed origins and destinations (i.e., intra-zonal trips) and those with origins or destinations concentrated at a set of fixed transit stations (i.e., first- or last-mile trip legs) at the same time. Each queuing model is integrated with the transit network design model, through proper service region partition, to derive closed-form formulas for the agency and passenger costs. Then, we formulate constrained non-linear programs that simultaneously optimize the zone partition, the fleet size and repositioning operation for the local DRT service, as well as the spacing and headway of a grid transit network. We apply the proposed models to a variety of transit technologies and application scenarios, so as to demonstrate applicability of the models, and to show promising performance of the proposed systems.

An Improved DC Line Fault Detection Scheme Using Zone Partition for MTDC Wind Power Integration Systems

The MMC based DC grids are an effective solution to integrate bulk wind power. Under DC faults, the wind power is continuously fed into DC grids, resulting in large fault currents. To guarantee the uninterrupted and safe operation of healthy parts, DC faults should be detected and isolated selectively. Most existing DC fault detection schemes rely on large current-limiting reactors (CLR) to guarantee high selectivity. The reliability of them will be deteriorated under weak boundary conditions. Besides, some schemes fail to identify close-in faults. Though fault detection schemes independent of CLRs are proposed, they cannot work well for remote faults. Hence, to protect the entire transmission line with smaller CLRs, an improved DC fault detection scheme using zone partition is proposed. Firstly, according to different fault distances, internal faults are partitioned into four zones along the transmission line. The fault characteristics in different zones are analyzed. Then, the polarities and arrival times of traveling-waves are used to design the criteria dedicated to different zones. The proposed method is endurable to fault resistance and noise disturbance. Simulation results show that the MTDC wind power integration systems can operate safely during DC fault isolation.