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The asymmetric operation is a method that allows High and Extra-High Voltage (HV, EHV) power lines to function with one or two phases open. With the increasing share of Renewable Energy Sources (RES) in National Power Systems (NPS), they are becoming more volatile and less reliable due to decreasing inertia and other issues related to the integration and exploitation of the Inverter-Based Resources (IBR) (decreasing short-circuit ratio, different types of interactions, etc.). On the other hand, phase-to-ground faults are a common cause of tripping off power lines which affects the overall reliability of the power system. Thus, for power systems experiencing a decreasing trend in reliability and robustness, the asymmetrical operation of the power lines may enhance them. In this way, this article reviews the state of the art and new developments in the academic landscape regarding asymmetrical operation. The review is not, however, limited to HV and EHV systems, so it examines cases of asymmetric operation in Low and Medium Voltages (LV, MV) as well. The challenges and opportunities that this unique mode of operation imposes on power networks are also presented, providing a fresh reference for researchers looking to enter this topic.

The large size of the sub-module (SM) capacitor is a typical problem in traditional modular multilevel converter-type solid-state transformers (MMC-SSTs). The MMC-SST based on high-frequency link interconnection is an effective solution for achieving lightweight capacitance. This structure can help to eliminate the symmetric SM fluctuating power, thereby reducing the SM capacitance. In a three-phase interconnected MMC-SST with low capacitance, potential risks may arise during transient processes, especially in cases of three-phase voltage asymmetry, such as large fluctuations in the SM voltage and unstable DC bus voltage. Aiming to solve this problem, this article re-analyzes the internal power characteristics of the MMC-SST under asymmetric operation and re-derives the SM capacitance constraint suitable for different degrees of three-phase voltage asymmetry. The new SM capacitance constraint enhances the asymmetric voltage ride-through capability of the MMC-SST. The new capacitance constraint is higher than that in symmetric operation, but it still has significant advantages in capacitance compared with the traditional MMC-SST.

To solve the negative-sequence temperature-rise problem of large equipment under asymmetric operating conditions, this paper optimizes the structure of the main components and adopts an improved process neural network to conduct online analysis and calculate the operating data, achieving the accurate prediction of the equipment heating status. Firstly, taking a 300 MW generator that urgently needs equipment improvement as the research object, the typical asymmetric accident characteristics that have occurred in recent years and the main influencing factors of negative-sequence heating of the rotor are analyzed. The influence of the rotor damping structure and shaft length on the temperature-rise change is explored. Secondly, a tent map is introduced to enhance the distribution uniformity of the population in the search space to enhance the global convergence of niche genetic algorithms. Numerical experiments and field experiments show that the improved algorithm, which is applied to optimize the parameters of the ridgelet process neural network, has good temperature-rise prediction performance. Finally, the influence of the rotor length and number of pole damping bars on the negative-sequence heating problem under different negative-sequence component ratios is examined, which provides useful references for the structural optimization and asymmetric operation state prediction of large equipment.

Embedded retaining walls equipped with ground heat exchangers is one kind of energy geostructures, harvesting the shallow ground energy for heating and cooling buildings. However, past investigations mainly focus on the thermal assessment of energy walls, but pay limited attention to mechanical wall behavior and associated ground response. At present, there is no standard preliminary code for assessing the long-term mechanical performance of energy walls. In this study, a comprehensive literature review is conducted to summarize the existing studies on the long-term mechanical behavior of both conventional retaining walls and thermo-active ones, respectively. The review identifies three most critical mechanical factors for energy walls (i.e., horizontal wall movement, ground settlement, and basement heave), while their permissible values can be referred to standard preliminary design criteria of conventional retaining walls in the short-term and limited long-term field measurements. For elaborating the application of design criteria, a parametric study is implemented to evaluate the long-term mechanical performance of energy walls in stiff clay under various thermal conditions, including the influence of thermal solicitations, station temperature and asymmetrical operation mode. The vivid assessing results show that the thermal-induced mechanical movements due to geothermal operation may cause unfavorable serviceability issues (e.g., cracks), but are unlikely to bring critical damages to the structural performance. The identified critical mechanical factors and evaluation of thermal influences in this study provide some guidance for the mechanical assessment of long-term energy wall behavior, particularly in the light of limited field measurements and demonstration cases.

Wave energy converters are attracting attention as an energy source that can respond to climate change. In order to increase the energy efficiency of the wave energy converters, efficient power converters are also required. The efficient converters require operation at a low switching frequency, which increases the weight and volume of the passive components. Therefore, in this paper, the performance of various types of topologies is compared to select the optimal power converter for wave energy converters. In order to cope with the unbalanced operation and unbalanced load of renewable energy, in this paper, the topology of the four-leg type is analyzed centrally. In addition, the analysis was performed by applying the model predictive control that can quickly respond to the rapid energy change of wave energy. In addition, model predictive control was applied to the four-leg converter analyzed in this paper because it is suitable for application to atypical topologies. For performance analysis of various types of topology, the loss and efficiency of each converter were analyzed by applying a loss analysis model, and output current harmonics and leakage current characteristics, capacitor voltage fluctuation rate, etc., were additionally analyzed at various switching frequencies. In conclusion, the three-level four-leg converter showed up to 2.28% and 2.7% higher efficiency under balanced and unbalanced operating conditions.

The emergence of the Internet of Things (IoT) and the tactile internet presents high-quality connectivity strengthened by next-generation networking to cover a vast array of smart systems. Quantum computing is another powerful enabler of the next technological revolution, which will improve the world tremendously, and it will continue to grow to cover an extensive array of important functions, in addition to it receiving recently great interest in the scientific scene. Because quantum computers have the potential to overcome various issues related to traditional computing, major worldwide technical corporations are investing competitively in them. However, along with its novel potential, quantum computing is introducing threats to cybersecurity algorithms, as quantum computers are able to decipher many complex mathematical problems that classical computers cannot. This research paper proposes a robust and performance-effective lattice-driven cryptosystem in the context of face recognition that provides lightweight intelligent bio-latticed cryptography, which will aid in overcoming the cybersecurity challenges of smart world applications in the pre- and post-quantum era and with sixth-generation (6G) networks. Since facial features are symmetrically used to generate encryption keys on the fly without sending or storing private data, our proposal has the valuable attribute of dramatically combining symmetric and asymmetric cryptography operations in the proposed cryptosystem. Implementation-based evaluation results prove that the proposed protocol maintains high-performance in the context of delay, energy consumption, throughput and stability on cellular network topology in classical Narrowband-Internet of Things (NB-IoT) mode.

A transmission network’s main objective is to continuously supply electrical energy to consumers. This article presents an analysis of the use of multi-circuit, multi-voltage overhead lines as a compromise between ensuring the system’s safe operation by increasing the transmission network capacity and managing the constraints related to its expansion. The considerations presented in this work include the construction of such lines, their operation, and modeling aspects. As part of the study, the potential for improving the environmental conditions around the lines is discussed in terms of the necessary area for their construction and the peak electromagnetic field strength in their vicinity. We also present a mechanical analysis of stress and sag coordination in the individual circuits of these lines. Then, we detail the method for determining the electrical parameters of multi-voltage lines’ series impedances and capacitance. Specific attention is given to the possibility of zero-sequence voltage that occurs in the systems despite the symmetric supply and load of circuits—especially in the circuits with the lowest voltages—that result from the line’s geometric asymmetry. We evaluate the impact of the line’s geometric asymmetry on the power system’s correct operation by determining the asymmetry factors. Finally, the accuracy of using a simplified symmetric model for lines with various geometric asymmetries is analyzed by studying the error of the short-circuit currents.

The future conflicts will take place in increasingly complex operational environments and will largely include conventional, asymmetric or hybrid opponents. The battle space that has acquired new valences and the asymmetrical nature of the current operational environment require the perpetual reconfiguration of the rules of engagement. Within the asymmetric actions, the enemy will focus their efforts on attacking vulnerable military structures, which have a degree of protection inadequate for the operational situation. Therefore, the protection of force is a key element in the effective management of situations, maintaining the pace of actions and the ability to fight in the development of asymmetric operations. From the range of asymmetric actions that manifests itself globally, we aim to conduct an analysis focused on force protection measures specific to counterinsurgency, counter-guerrilla and counter-terrorism operations. The place and role of force protection in asymmetric operations attest to the fact that specific measures are aimed in particular at maintaining the morale and combat capability of their own forces throughout the range of missions performed, as well as protecting the civilian population in the area of action.

We study the online market for peer-to-peer (P2P) lending, in which individuals bid on unsecured microloans sought by other individual borrowers. Using a large sample of consummated and failed listings from the largest online P2P lending marketplace, Prosper.com, we find that the online friendships of borrowers act as signals of credit quality. Friendships increase the probability of successful funding, lower interest rates on funded loans, and are associated with lower ex post default rates. The economic effects of friendships show a striking gradation based on the roles and identities of the friends. We discuss the implications of our findings for the disintermediation of financial markets and the design of decentralized electronic markets. This paper was accepted by Sandra Slaughter, information systems.

Prior literature has shown that, for a symmetric information setting, supplier encroachment into a reseller's market can mitigate double marginalization and benefit both the supplier and the reseller. This paper extends the investigation of supplier encroachment to the environment where the reseller might be better informed than the supplier. We find that the launch of the supplier's direct channel can result in costly signaling behavior on the part of the reseller, in which he reduces his order quantity when the market size is small. Such a downward order distortion can amplify double marginalization. As a result, in addition to the \"win-win\" and \"win-lose\" outcomes for the supplier and the reseller, supplier encroachment can also lead to \"lose-lose\" and \"lose-win\" outcomes, particularly when the reseller has a significant efficiency advantage in the selling process and the prior probability of a large market is low. We further explore the implications of those findings for information management in supply chains. Complementing the conventional understanding, we show that with the ability to encroach, the supplier may prefer to sell to either a better informed or an uninformed reseller in different scenarios. On the other hand, as a result of a supplier developing encroachment capability, a reseller either may choose not to develop an advanced informational capability or may become more willing to find a means of credibly sharing his information. This paper was accepted by Yossi Aviv, operations management.