External Operation Research Articles

Multi-physical quantities sensing based on the nematic liquid crystal Janus metastructure in theory

Breaking through the idea limitation of traditional single-scale and single-function sensors, a multi-scale and multi-function Janus metastructure (JMS) is proposed in this article, which is constructed by the specific methods to break its parity. Using the change of transmission spectrum, JMS can realize multi-physical quantities detection with different sensing performances, when electromagnetic waves propagate on positive and negative scales respectively. For selective gas detection, JMS can conveniently detect 0–3.5 % methane concentrations with sensitivity (S) of 22.932 THz/RIU and 0–3 % hydrogen concentrations with S of 43.494 THz/RIU, avoiding the problem of complex and dangerous external operation conditions required for previous gas sensors. Based on the electro-optical effect of nematic liquid crystal, JMS can realize wide-range electric field direction (EFD) sensing of 10°–80° and 100°–170° by taking the advantages of multi-scale detection, which is wider than existing 0°–90° EFD sensors. Because nematic liquid crystal is thermotropic, JMS can also achieve accurate temperature detection of 283.15–318.15 K. Finally, through comparison, it is proved that JMS proposed has the potential of multi-scenario applications, and meets the urgent demand for excellent performance sensors in the fields of dangerous gas transportation, atmospheric EFD detection and industrial manufacturing temperature control.

Degradation prediction of fuel cell systems based on different operating conditions in dynamic cycling condition

In this paper, the degradation of PEMFC under different operating conditions in dynamic cycle condition is studied. Firstly, according to the failure mechanism of PEMFC, various operating conditions in dynamic cycle condition are classified, and the health indexes are established. Simultaneously, the rates and degrees of the output voltage decline of the PEMFC under different operating conditions during the dynamic cycling process were compared. Then, a model based on variational mode decomposition and long short-term memory with attention mechanism (VMD-LSTM-ATT) is proposed. Aiming at the performance of PEMFC is affected by the external operation, VMD is used to capture the global information and details, and filter out interference information. To improve the prediction accuracy, ATT is used to assign weight to the features. Finally, in order to verify the effectiveness and superiority of VMD-LSTM-ATT, we respectively apply it to three current conditions under dynamic cycle conditions. The experimental results show that under the same test conditions, RMSE of VMD-LSTM-ATT is increased by 56.11 % and MAE is increased by 28.26 % compared with GRU attention. Compared with SVM, RNN, LSTM and LSTM-ATT, RMSE of VMD-LSTM-ATT is at least 17.26 % higher and MAE is at least 5.65 % higher.

Recent advances and prospects of constructed wetlands in cold climates: a review from 2013 to 2023.

Constructed wetland (CW), a promising, environmentally responsible, and effective green ecological treatment technology, is actively involved in the treatment of various forms of wastewater. Low temperatures will, however, lead to issues including plant dormancy, decreased microbial activity, and ice formation in CWs, which will influence how well CWs process wastewater. Applying CWs successfully and continuously in cold areas is extremely difficult. Therefore, it is crucial to find solutions for the pressing issue of increasing the CWs' ability to process wastewater at low temperatures. This review focuses on the effect of cold climate on CWs (plants, substrates, microorganisms, removal effect of pollutants). It meticulously outlines current strategies to enhance CWs' performance under low-temperature conditions, including modifications for the improvement and optimization of the internal components (i.e., plant and substrate selection, bio-augmentation) and enhancement of the external operation conditions of CWs (such as process combination, effluent recirculation, aeration, heat preservation, and operation parameter optimization). Finally, future perspectives on potential research directions and technological innovations that could strengthen CWs' performance in cold climates are prospected. This review aims to contribute valuable insights into the operation strategies, widespread implementation, and subsequent study of CWs in colder climate regions.

Electric field enhancement of the superconducting spin-valve effect via strain-transfer across a ferromagnetic/ferroelectric interface

In a ferromagnet/superconductor/ferromagnet (F/S/F) superconducting spin-valve (SSV), a change in the magnetization alignment of the two F layers modulates the critical temperature (Tc) of the S layer. The Tc-switching effect (the SSV effect) is based on the interplay between superconductivity and magnetism. The fast and large resistive switching associated with Tc-switching is suitable for nonvolatile cryogenic memory applications. However, the external magnetic field-based operation of SSVs is hindering their miniaturization, and therefore, electric field control of the SSV effect is desired. Here, we report epitaxial growth of a La0.67Ca0.33MnO3/YBa2Cu3O7/La0.67Ca0.33MnO3 SSV on a piezo-electric [Pb(Mg0.33Nb0.67)O3]0.7-[PbTiO3]0.3 (001) substrate and demonstrate electric field control of the SSV effect. Electric field-induced strain-transfer from the piezo-electric substrate increases the magnetization and Tc of the SSV and leads to an enhancement of the magnitude of Tc-switching. The results are promising for the development of magnetic-field-free superconducting spintronic devices, in which the S/F interaction is not only sensitive to the magnetization alignment but also to an applied electric field.

A CA-LBM framework for simulating the lithium dendrite growth process

The Lithium metal batteries with high energy density are limited for further commercial applications by the formation of Lithium dendrites, which is difficult to regulate due to its complex growth mechanism. In order to investigate the relationship between the dendritic morphology inside the electrode and the external operation conditions, a two-dimensional simulation framework based on the cellular automaton (CA) and the Lattice Boltzmann method (LBM) is proposed. In this framework, the simulation region is divided into discrete grids and each grid includes a cell to record the phase state and the concentration at the position. Meanwhile, the phase transition rule is set in the CA model and the concentration field is solved by LBM. Based on this framework, the impact of the applied voltage and the diffusion coefficient on the dendritic morphology is investigated. The simulation results indicate that the growth rate and the bifurcation rate of Lithium dendrites can both be reduced by applying lower operating voltage and higher diffusion coefficient which is critical in regulating the morphology of Lithium dendrites.

MuST: Robust Image Watermarking for Multi-Source Tracing

In recent years, with the popularity of social media applications, massive digital images are available online, which brings great convenience to image recreation. However, the use of unauthorized image materials in multi-source composite images is still inadequately regulated, which may cause significant loss and discouragement to the copyright owners of the source image materials. Ideally, deep watermarking techniques could provide a solution for protecting these copyrights based on their encoder-noise-decoder training strategy. Yet existing image watermarking schemes, which are mostly designed for single images, cannot well address the copyright protection requirements in this scenario, since the multi-source image composing process commonly includes distortions that are not well investigated in previous methods, e.g., the extreme downsizing. To meet such demands, we propose MuST, a multi-source tracing robust watermarking scheme, whose architecture includes a multi-source image detector and minimum external rectangle operation for multiple watermark resynchronization and extraction. Furthermore, we constructed an image material dataset covering common image categories and designed the simulation model of the multi-source image composing process as the noise layer. Experiments demonstrate the excellent performance of MuST in tracing sources of image materials from the composite images compared with SOTA watermarking methods, which could maintain the extraction accuracy above 98% to trace the sources of at least 3 different image materials while keeping the average PSNR of watermarked image materials higher than 42.51 dB. We released our code on https://github.com/MrCrims/MuST

Outcome of External Dacryocystorhinostomy Operation with and without Posterior Nasal Mucosal Flap Suturing Technique in Combined Military Hospitals of Bangladesh

Introduction: External Dacryocystorhinostomy is an anastomosing operation which creates a fistula between the medial wall of lacrimal sac and lateral wall of nasal cavity. Objectives: To compare the success rate by suturing both the anterior and posterior nasal mucosal flaps and without suturing the posterior nasal mucosal flap in External DCR surgery of 50 cases in different Combined Military Hospitals (CMH) of Bangladesh. Methods: The study included 50 cases of Chronic Dacryocystitis patients with symptoms of epiphora and blocked Sac Patency Test (SPT). External Dacryocysto- rhinostomy (DCR) surgery was done by same surgeon in different CMH over the period of 02 years extending from January 2016 to December 2017. Total 50 patients were divided into equal 02 groups. Group A underwent External DCR with silicone tube intubation and both anterior and posterior nasal mucosal flaps were sutured. Group B underwent similar DCR surgery where only anterior nasal mucosal flaps were sutured with lacrimal sac flap and posterior mucosal flap was excised completely. Results: External DCR surgery success rate was evaluated by a patent SPT at 03 months, 06 months and 12 months post operatively in both groups. SPT was successful in 92% cases in group A and 96% in group B at 3 months follow up after silicone tube removal. At 6 months reduction of epiphora occurred in 90% cases in Group A and 96% cases in Group B with unchanged SPT percentage. At 12 months follow up result remained unchanged as found at 6 months. There was significant difference in success rate of two different surgical technique. Quality of surgery improved with less intraoperative complications with shorter surgical time when only anterior nasal mucosal flap was sutured with excision of posterior nasal flap. Conclusion: This study suggested that comparing both the techniques of with and without suturing anterior and posterior nasal mucosal flaps in external DCR surgery, the later one makes considerable improvement in success rate of DCR. Excising the posterior nasal mucosal flaps can reduce operation time, improve operation technique and reduced epiphora post surgically. JAFMC Bangladesh. Vol 19, No 1 (June) 2023: 31-33

Enhancing Logistics Distribution Efficiency for Indonesian Navy Warships in Operations Area

The Indonesian Navy faces challenges in maintaining the readiness of warships deployed in external operation areas due to inefficiencies in logistics distribution. Understanding current practices and identifying bottlenecks is crucial for devising strategies to enhance logistics efficiency. This study aims to investigate the current logistics distribution practices of the Indonesian Navy, identify primary bottlenecks and inefficiencies, explore opportunities for optimization, and propose strategies for increasing logistics distribution efficiency to support warships in external operation areas. Utilizing Creswell's qualitative research framework, this study analyzes existing secondary data from academic journals, reports, and governmental documents related to naval logistics in Indonesia. The study reveals the current logistics distribution practices and procedures of the Indonesian Navy, identifies primary bottlenecks and inefficiencies within the existing system, explores opportunities for optimization of logistics processes and infrastructure, and proposes a comprehensive strategy for increasing logistics distribution efficiency to support the readiness of Indonesian Navy warships in external operation areas. By leveraging qualitative research methods and secondary data analysis, this study provides valuable insights into enhancing logistics distribution efficiency for Indonesian Navy warships, contributing to improved readiness and operational effectiveness in external operation areas.

Amphibious Architecture: A Biomimetic Design Approach to Flood Resilience

Amphibious buildings use the buoyancy principle in the design of their foundation systems to mitigate flood impact. In some cases, amphibious buildings are fitted with mechanical systems that further aid the buoyancy element to temporarily raise the building and guide its descent to natural ground level. These mechanical systems require external operation, preventing the amphibious building from passively responding during flood events as is one of the requirements of a robust flood mitigation measure. Additionally, buildings in flood environments are often left with stains on the exterior facade from floodwater contamination from sewage and chemicals, among others. This paper distinguishes three main components of an amphibious foundation: the buoyancy element, vertical guidance post, and structural sub-frame, and discusses their functionality. The natural world provides solutions to tackling environmental issues such as flooding. When systematically studied and transferred, nature can inspire innovative ideas for functional and sustainable designs for the built environments. Although there are many existing designs and a small number of constructed amphibious buildings, there are very few studies that discuss how the designs are derived, and even fewer on a framework emulating natural systems for transfer into amphibious building design. In that context, this research uses the biomimetic transfer process to abstract relevant biological systems, illustrating their potential for transfer into amphibious foundation design. The aim is to understand how these biological systems passively and continuously respond and adapt to their environment. Organisms such as the Venus flower basket, giant kelp, and red mangrove, among others, are discussed, to understand how they perform the identified functions. The steps of the biomimetic transfer process are used to integrate functions of amphibious buildings and processes of the studied biological systems. The final output of this paper is a discussion of the ways in which these derived relationships can be adopted in amphibious building design.

Bone transport combined with sequential nailing technique for the management of large segmental bone defects after trauma.

Bone transport technique is widely used for the management of large segmental bone defects. However, several reasons may prevent its successful completion, such as poor osteogenesis, docking site nonunion, severe chronic pain and psychological problems. We used sequential nailing technique to solve these problems. The objective of this study was to analyze the clinical effects of our modified technique for the management of large segmental bone defects after trauma. Twenty-three patients using bone transport combined with sequential nailing technique in our institution from June 2011 to June 2020 were included and analyzed retrospectively. There were 15 males and eight females. The age ranged from 19 to 64 years. There were eight cases suffering from basic medical diseases. The initial injury was open in 14 patients. Seven cases encountered femoral defects and 16 for tibia. The main reasons for sequential nailing technique were docking site nonunion (nine cases), poor osteogenesis (five cases), severe chronic pain (five cases) and psychological problems (four cases). The residual bone defects after removing the external fixator, operation plans, complications and follow-up time were recorded. Bone defect healing was evaluated by Paley score. The mean residual bone defects were (2.9 ± 1.9) cm. The mean time in external fixator was (9.5 ± 3.4) months. The average follow-up time was (23 ± 3) months. With respect to complications, two cases suffered from nonunion again and were treated by bone graft with augmented plate fixation. No infection recurrence was found in these cases. The excellent and good rate of bone defect healing was 91.3%. Bone transport combined with sequential nailing technique could shorten the external fixation time, overcome the inconvenience of the external frame to patients, eliminate chronic pain and be easy for patients to accept. Patients using this modified technique achieved high satisfaction.

Seismic retrofitting of an existing hospital with external steel brace

Earthquakes may cause serious damage to buildings and result in heavy losses to society, therefore, it is necessary to enhance the seismic capacity of existing buildings via structural retrofitting. The traditional retrofitting approaches are based on the component-level, but their improvement effect for the overall structure is not obvious. Until now, the seismic retrofitting technology can be generally divided into three types. The first is strength-improving type, the second is ductility-improving type, and the third is seismic dissipation/isolation type. Commonly a combination of these three types is used in retrofitting solutions. Most of them are focused on member based or component-level improvements of strength and/or ductility applied to poorly reinforced concrete walls or columns and masonry walls. Meanwhile, the weak element of the existing structure can be strengthened by external sub-structures as steel frames to make the overall structural capacity or stiffness more uniform. In addition, because the construction is an external operation, it can achieve non-disturbing retrofitting without affecting the normal use of the inner structure, which is of great practical significance and social benefits for lifeline projects such as schools and hospitals that cannot be interrupted. In the present case study, the efficiency of a seismic retrofitting with external steel frame of the university hospital Zurich (USZ) will be discussed. The original 3-story reinforced concrete building with a rectangular floor plan of 44m x 24m was built in 1966. Subsequently, in 1970, the building was extended by 4 floors with a composite steel structure. On the roof floor there is a helipad for emergencies. The stiffening steel structure was connected to the building with post-installed anchors. The first results of a response spectrum analysis showed major deficiencies in terms of horizontal and torsional stiffness, so that a strengthening measure became necessary. The results were verified by means of a push-over analysis, which showed that the measure applied was very effective. Finally, the structural design and the connection details to the existing concrete structure are shown.

Establishment of a Constraint Model for the External Operation of University Sports Venues

Establishment of a Constraint Model for the External Operation of University Sports Venues

Study of the Relationship Between Temperature Change and Energy Transfer in Thermodynamic Processes in Buildings

In this paper, the relationship between room temperature and outside temperature, wall temperature, system operation, and energy consumption is investigated through mathematical modeling and simulation experiments. The thermodynamic parameters of a typical room are used in the study, and the characteristics of the heating and cooling system are considered. 1. This paper analyses the variation of room temperature, wall temperature, switching state, and heating power with time. The results show that the room and wall temperatures are influenced by the external temperature and system operation, while the switching state and heating power are regulated by the room temperature. The correlation between temperature and heating power is quantified by calculating the correlation coefficient matrix. The results show that there is a positive correlation between room temperature and heating power, while there is a negative correlation between wall temperature and room temperature and heating power. 2. This paper investigates the effect of external temperature on room temperature and wall temperature. The results show that an increase in external temperature leads to a decrease in room temperature and wall temperature. In addition, it is found that the indoor temperature is more sensitive to changes in external temperature within the range of changes in external temperature. 3. It is based on the steady-state solution curves between temperature and external temperature, as well as thermodynamic plots of system operation and energy consumption. The visual presentation of the effect of external temperature on the system provides a reference for optimizing building energy use and designing efficient heating and cooling systems. This study provides insight into the relationship between temperature change and energy transfer in building thermodynamic processes, guiding for achieving sustainable energy utilization and reducing environmental impacts. It is of great significance for optimizing the design of building energy systems and improving the efficiency of energy use.

Self-Aware Cybersecurity Architecture for Autonomous Vehicles: Security through System-Level Accountability.

The inherent dynamism of recent technological advancements in intelligent vehicles has seen multitudes of noteworthy security concerns regarding interactions and data. As future mobility embraces the concept of vehicles-to-everything, it exacerbates security complexities and challenges concerning dynamism, adaptiveness, and self-awareness. It calls for a transition from security measures relying on static approaches and implementations. Therefore, to address this transition, this work proposes a hierarchical self-aware security architecture that effectively establishes accountability at the system level and further illustrates why such a proposed security architecture is relevant to intelligent vehicles. The article provides (1) a comprehensive understanding of the self-aware security concept, with emphasis on its hierarchical security architecture that enables system-level accountability, and (2) a deep dive into each layer supported by algorithms and a security-specific in-vehicle black box with external virtual security operation center (VSOC) interactions. In contrast to the present in-vehicle security measures, this architecture introduces characteristics and properties that enact self-awareness through system-level accountability. It implements hierarchical layers that enable real-time monitoring, analysis, decision-making, and in-vehicle and remote site integration regarding security-related decisions and activities.

Recent progress of enhanced bubble separation in alkaline water electrolyzer

Alkaline water electrolysis has a large industrial application and development potential in hydrogen energy owing to its high maturity and low cost. However, its moderate energy efficiency, especially caused by bubble effects, inhibits its use for large-scale hydrogen production. To overcome this shortcoming, this review first analyzes the bubble effect and summarizes the external operation methods, such as external field intensification, flow operation, fluctuation operation, and surfactant addition to the electrolyte, to enhance bubble separation in the electrolyzer. Then, electrode and flow channel structure optimization, particularly superhydrophilic and superaerophobic electrodes, and flow channels with varying heights, square column arrangements, and inlet/outlet numbers are highlighted. Finally, future research directions in alkaline water electrolysis technology are suggested to advance the industrial application of large-scale alkaline water electrolysis.

Performance optimization of the air-cooling system in a coal-fired power unit based on intelligent algorithms

Air-cooled condensing technology is considered a preferred technology for thermal power generation due to the advantages of water savings. The performance of air-cooled condenser (ACC) is mainly influenced by external weather conditions and unit operation. In this paper, an artificial intelligence algorithm model is developed to predict and optimize the performance of the air-cooled condenser in advance based on long-term operational data of coal-fired power plants. A back propagation neural network algorithm is used to establish a net power output-back pressure model, and the optimal back pressure search is completed based on the established model. Finally, the average power savings of a single sample over a 30-second period was used as an indicator to evaluate the energy saving effect of optimized back pressure. The artificial intelligence analysis method not only enables the use of a large amount of operational data, but also allows effective prediction, analysis, and optimization of the performance of the air-cooled condenser, ultimately improving the overall performance of this equipment. The results indicate that: (1) when the back pressure of the unit reaches 9.25 kPa, the net power output of the unit is the highest, thus achieving the optimal back pressure; (2) by calculating the average energy savings, it can be concluded that, for a single sample over a 30-second period, the average power savings of the unit are above 7.0 kWh during the medium load period, and 5.0 kWh during the low and high load periods. Therefore, the proposed optimization method is beneficial for energy saving of the air-cooled condenser.

Analytical Approach by Sorting of Manure for Farming and Electricity from Municipality Solid Waste

Waste operation and declining soil fertility are the main issues endured by all developing nations, like India. Currently, agrarian application of Municipal Solid Waste (MSW) is one of the most promising and cost effective options for managing solid waste. It's helpful in working current burning issues viz. soil fertility and MSW operation still there's always a implicit trouble because MSW may contain pathogens and poisonous adulterants. Thus important emphasis has been paid to composting of MSW in recent times operation of compost from MSW in agrarian land helps in upgrading the soil’s physico- chemical parcels. Piecemeal from that it also assists in perfecting natural response of cultivated land. Keeping the present situation in mind, this review critically discusses the current script, agrarian application of MSW compost and energy from part of soil microbes and soil microbial response on external solid waste compost operation.

Soliton Microcombs Multiplexing Using Intracavity-Stimulated Brillouin Lasers.

Solitons in microresonators have spurred intriguing nonlinear optical physics and photonic applications. Here, by combining Kerr and Brillouin nonlinearities in an over-modal microcavity, we demonstrate spatial multiplexing of soliton microcombs under a single external laser pumping operation. This demonstration offers an ideal scheme to realize highly coherent dual-comb sources in a compact, low-cost and energy-efficient manner, with uniquely low beating noise. Moreover, by selecting the dual-comb modes, the repetition rate difference of a dual-comb pair could be flexibly switched, ranging from 8.5 to 212MHz. Beyond dual-comb, the high-density mode geometry allows the cascaded Brillouin lasers, driving the co-generation of up to 5 space-multiplexing frequency combs in distinct mode families. This Letter offers a novel physics paradigm for comb interferometry and provides a widely appropriate tool for versatile applications such as comb metrology, spectroscopy, and ranging.

A study on optimization of delayed production mode of iron and steel enterprises based on data mining.

Delayed production mode has been adopted by an increasing number of process production enterprises as a method to realize mass customization of multi-products. This paper used the convolutional neural network-long short-term memory artificial neural network algorithm (C-LSTM) in data mining technology to analyze and determine factors that have an impact on delayed production mode in the internal and external production and operation of enterprises. Combined with the actual production situation of iron and steel enterprises, a quantitative model of the delayed production was constructed. Lastly, data from a large iron and steel enterprise with good operation was used to verify the validity of the proposed model and analyze key influencing factors. According to the research, in scenarios of considering PDP alone, considering CODP alone, considering both PDP and CODP, considering PDP and CODP and using data mining technology to model, the matching degree of these methods with the actual situation of the enterprise is 31.8%, 61.4%, 71.6% and 86.6%, respectively. The numerical analysis results of the model based on data mining technology show that in delayed production, when customer service level improves or the delay penalty coefficient increases, the optimal locations of the product differentiation point (PDP) and customer order decoupling point (CODP) move toward the end of production, and the total cost increases gradually. When the difference in production cost or benefit of early delivery between the candidate locations of PDP and CODP is small, optimal locations of PDP and CODP are close to the beginning of the general and dedicated production processes. With an increase of cost difference or early delivery benefit, the optimal locations of PDP and CODP jumped to the end stage of the general and dedicated production processes, and the total cost begins to decrease.

Sizing-design method for compressed air energy storage (CAES) systems: A case study based on power grid in Ontario

Correctly sizing a compressed energy storage (CAES) system by considering external power grid requirements, component limitations, and operation restrictions is essential to successfully enhancing a CAES system’s usability and effectiveness. A new method, referred to as the coverage-percentage method, is developed and applied to Ontario as a case study, to size a CAES system based on its percentage ability to capture excess energy and deliver energy during a shortage. The coverage-percentage method builds upon and improves upon the frequency-of-occurrence method proposed by Rouindej et al. (2019) by adding time dependent operation considerations (cavern pressure and temperature), and component limitations (compressor, expander, and cavern sizes). These additional considerations improve both sizing accuracy and usability understanding. One major advantage of the coverage-percentage method is that it rectifies the overestimation of the frequency-of-occurrence method with regards to the percentage of excess energy that can be stored, and stored energy that can be delivered, for a given sized expander, compressor, and cavern. For example, it is observed that a cavern size of 950 MWh for Ontario can capture and deliver 85% of excess energy, while the coverage-percentage method results reveal that a cavern of 950 MWh can actually only cover 48% of Ontario’s charging potential. These significantly differing results between the frequency-of-occurrence method and the coverage-percentage method because of the interplay of expander, compressor, and cavern sizes not considered in the frequency-of-occurrence method, but most critically because cavern damaging pressure and temperature limits are not considered in the frequency-of-occurrence method. By applying the coverage-percentage method to 2018 to 2020 Ontario electrical grid data, and to a salt cavern with pressure limits between 5 MPa and 14 MPa, it is revealed that compressors sized between 30 MW to 70 MW, expanders sized between 40 MW to 90 MW, and cavern energy capacities between 630 MWh and 770 MWh would be sufficient to capture at least 42% and 26% of charging and discharging opportunities, respectively.