Operational Space Research Articles

144. OPTIMIZING MEDIASTINAL ACCESS FOR RADICAL ESOPHAGECTOMY: A BILATERAL CERVICAL AND TRANSHIATAL APPROACH TO RESECT ESOPHAGEAL CANCER

Abstract Background Major medical centers have gradually attempted and promoted esophagectomy via mediastinal approach. However, this operation is challenging and requires a high level of technical proficiency from surgeons because of the limited space and restricted visibility of the mediastinum. The current surgical method limits its application in patients with locally advanced esophageal cancer, which underscores an urgent need for optimization to facilitate its refinement and dissemination. Methods We have implemented the following enhancements to the surgical procedure: 1. The cervical level was chosen for transecting the esophagus, and then the proximal esophageal stump was pulled down and invaginated. 2. Bilateral cervical incisions were made, with a small 0.5 cm incision at the anterior edge of the right sternocleidomastoid muscle. 3. The position of abdominal surgical incisions was adjusted so that all incisions were located on the left side of the abdominal midline. 4. A portion of the left diaphragm was dissected. 5. During the superior mediastinum procedure, gauze was positioned within the expanded superior mediastinum. Results 1. The surgical field was fully exposed, expanding the operative space for upper mediastinal surgery. 2. The difficulty of this surgery was reduced, and it was easier to expose both RLNs and completely remove the mediastinal lymph nodes. 3. The 106recR could be completely removed under endoscopy. 4. The thoracic duct could be fully exposed and freed. 5. During surgery, gauze is placed in the upper mediastinum to aid in hemostasis and improve visibility. 6. Even if the tumor was slightly larger or locally invaded surrounding tissues, it could be completely resected. 7.Complete resection of the esophageal mesorectum was successfully achieved. Conclusion Esophagectomy for esophageal cancer via bilateral cervical and transhiatal approach can achieve radical resection and can be applied to patients with locally advanced esophageal cancer. This surgical method expands the surgical indications, reduces the surgical difficulty for surgeons, and facilitates the promotion and popularization of the mediastinal approach surgery.

Global food trade alleviates transgressions of planetary boundaries at the national scale

Food systems are among the leading causes for transgression of planetary boundaries globally, which define the safe operating space for humanity. We quantify unsustainable environmental impacts of food systems, indicated by the transgression of national-scale planetary boundaries (i.e., the safe operating space for food production in each country), from both production and consumption perspectives of 189 countries/regions around the world. A multi-regional input-output model is used to map the global transfers of the national-scale transgression of planetary boundaries, including freshwater use, land change, and biogeochemical flows (nitrogen and phosphorus). Our results show that China is a major global unsustainable water and nitrogen exporter and an unstable land and phosphorus importer. This means that water and nitrogen uses in China are used to support food demands in other countries, and food consumption in China requires unsustainable land and phosphorus uses elsewhere. In contrast, the US is a major exporter of unsustainable water, land, and nitrogen uses but only an importer of unsustainable phosphorus for food consumption. Globally, compared to a counterfactual scenario where there is no food trade among any countries, food trade saves massive transgressions of planetary boundaries (270km3 of water, 18 million tons of nitrogen, 7 million tons of phosphorus, and 5,431 million km2 of land). Alleviation of national-scale planetary boundary transgression has been achieved primarily in the US, China, Saudi Arabia, etc., while aggravation was incurred in Pakistan, Australia, Argentina, and so forth.

175. OPTIMIZING MEDIASTINAL ACCESS FOR RADICAL ESOPHAGECTOMY: A BILATERAL CERVICAL AND TRANSHIATAL APPROACH TO RESECT ESOPHAGEAL CANCER

Abstract Background Major medical centers have gradually attempted and promoted esophagectomy via mediastinal approach. However, this operation is challenging and requires a high level of technical proficiency from surgeons because of the limited space and restricted visibility of the mediastinum. The current surgical method limits its application in patients with locally advanced esophageal cancer, which underscores an urgent need for optimization to facilitate its refinement and dissemination. Methods We have implemented the following enhancements to the surgical procedure: 1. The cervical level was chosen for transecting the esophagus, and then the proximal esophageal stump was pulled down and invaginated. 2. Bilateral cervical incisions were made, with a small 0.5 cm incision at the anterior edge of the right sternocleidomastoid muscle. 3. The position of abdominal surgical incisions was adjusted so that all incisions were located on the left side of the abdominal midline. 4. A portion of the left diaphragm was dissected. 5. During the superior mediastinum procedure, gauze was positioned within the expanded superior mediastinum. Results 1. The surgical field was fully exposed, expanding the operative space for upper mediastinal surgery. 2. The difficulty of this surgery was reduced, and it was easier to expose both RLNs and completely remove the mediastinal lymph nodes. 3. The 106recR could be completely removed under endoscopy. 4. The thoracic duct could be fully exposed and freed. 5. During surgery, gauze is placed in the upper mediastinum to aid in hemostasis and improve visibility. 6. Even if the tumor was slightly larger or locally invaded surrounding tissues, it could be completely resected. 7.Complete resection of the esophageal mesorectum was successfully achieved. Conclusion Esophagectomy for esophageal cancer via bilateral cervical and transhiatal approach can achieve radical resection and can be applied to patients with locally advanced esophageal cancer. This surgical method expands the surgical indications, reduces the surgical difficulty for surgeons, and facilitates the promotion and popularization of the mediastinal approach surgery. Video address: https://www.icloud.com.cn/iclouddrive/085wyZDN6Qqm6Ou06fhOsi-Rw#2023_ISDE_abstract_video

Experimental Study on the Static Behavior and Recovery Properties of CFRP/SMA Composites

Strengthening reinforced concrete elements with externally bonded prestressed fiber reinforced polymer (FRP) sheets has become a popular reinforcement technology in recent years. However, in practical engineering applications, due to the limitations of construction operation space and the need for specialized design of tensioning and anchoring devices, it is very cumbersome to apply prestressing force to FRP sheets. Therefore, using the recovery effect of shape memory alloys (SMA) to introduce prestressing into FRP sheets can innovate a new approach by combining FRP sheets and SMA wires. In order to study the basic mechanical properties of FRP/SMA composites, carbon fiber reinforced polymer and shape memory alloys were used to make the composite specimens, and uniaxial tensile tests were carried out on them. The mechanical properties such as the stress-strain curve, failure mode, ultimate tensile strength and fracture strain were obtained. The test results show that CFRP sheet exhibits obvious linear elastic behavior in tensile tests. The stress-strain curve of SMA wire can be divided into four stages: the linear elastic stage, yield stage, strengthening stage and failure stage. The fracture strain at failure can reach 7%, which indicates excellent deformation properties. The loading and unloading cycles have little effect on the mechanical properties of SMA wire. With the increase in the loading rate, the ‘stress plateau’ section of the phase transformation section of the SMA wire hysteresis curve gradually transits to an oblique upward curve. Increasing the pre-strain value within a certain range can improve the resilience of SMA wires. SMA wires with a pre-strain value of 8% can provide a maximum resilience of 514 MPa after heating to the austenitic state. A prediction model for the number of temperature cycles and maximum recovery force of SMA was proposed and validated. According to this model, the SMA wires can still provide stable resilience after 30 cycles. Increasing the amount of wire (volume ratio) can improve the maximum fracture strain and ultimate tensile strength of CFRP/SMA composite specimens, and the more wire is added, the greater the residual strength after fracture. The diameter of the fiber can significantly reduce the maximum fracture strain and ultimate tensile strength of the FRP/SMA composite specimen.

Comparasion of the anatomic and therapeutic effect of two transsphenoidal approaches under neuroendoscopy

ObjectiveTo compare anatomical parameters, postoperative nasal complications and quality of life of 2 sphenoid sinus approaches (nasal septum approach and transsphenoidal anterior wall approach) via anterior wall by endoscopic surgery. MethodsThe study was anatomic basis research and prospective randomized double-blind (Clinical trials registration number: NFEC-2015-033). Study was performed in 30 dissected heads via 2 approaches. The related anatomic parameters were measured. Another 60 patients with pituitary tumor were randomly divided into 2 groups to receive endoscopic surgery. The selected otolaryngologist and non-operative neurosurgeon common then analyzed preoperative indicators. The therapeutic effect and nasal complications of 2 transsphenoidal approaches were compared by Lund-Kennedy scale, Lund-Mackay scale and SNOT-20 scale. ResultsThe distances between incision and external nostrils of anterior wall in nasal septum approach and transsphenoidal anterior wall approach are 5.19 ± 0.15 versus 6.91 ± 0.14 cm, respectively; maximum angles and ranges of swing in horizontal direction on operative route are 44.77 ± 2.04° versus 38.54 ± 1.40°, and 1.25 ± 0.15 versus 0.59 ± 0.52 cm. The operation time in nasal septum approach group is shorter (61.97 ± 18.123 min) than transsphenoidal anterior wall approach group (89.83 ± 38.515 min); And higher Lund-Kennedy score (2.4737 ± 1.46699 vs 3.8125 ± 1.51520. In addition, 20 Subjective Scoring Scales for Nasal and Paranasal Sinus Outcome (SNOT-20) measurement results indicated nasal septum approach group has less subjective symptoms plague patients' lives. The cerebrospinal fluid leakage, resection of tumor, postoperative endocrine remission rate and postoperative complications occurred in 2 groups have no significant difference. ConclusionEndonasal transsphenoidal via nasal septum-sphenoid sinus approach has characters of less surgery damage, short distance to the outside of the nose, precise location, wider operation space and larger perspective, which is obvious advantages in reducing postoperative nasal complications.

Data-driven plasma modelling: surrogate collisional radiative models of fluorocarbon plasmas from deep generative autoencoders

We have developed a deep generative model that can produce accurate optical emission spectra and colour images of an ICP plasma using only the applied coil power, electrode power, pressure and gas flows as inputs—essentially an empirical surrogate collisional radiative model. An autoencoder was trained on a dataset of 812 500 image/spectra pairs in argon, oxygen, Ar/O2, CF4/O2 and SF6/O2 plasmas in an industrial plasma etch tool, taken across the entire operating space of the tool. The autoencoder learns to encode the input data into a compressed latent representation and then decode it back to a reconstruction of the data. We learn to map the plasma tool’s inputs to the latent space and use the decoder to create a generative model. The model is very fast, taking just over 10 s to generate 10 000 measurements on a single GPU. This type of model can become a building block for a wide range of experiments and simulations. To aid this, we have released the underlying dataset of 812 500 image/spectra pairs used to train the model, the trained models and the model code for the community to accelerate the development and use of this exciting area of deep learning. Anyone can try the model, for free, on Google Colab.

Dolenc approach for clipping of giant C6 and C7 segment aneurysms of the internal carotid artery.

Surgical treatment for giant aneurysms of the ICA-ophthalmic segment (C6) and communicating artery segment (C7) is a challenge for neurosurgeons because of their high risks and poor outcomes. We aim to explore the advantages and disadvantages of the Dolenc approach in the treatment of giant C6-C7 segment aneurysms. We retrospectively reviewed the clinical data of 13 cases with giant C6 aneurysms and 4 cases with giant C7 aneurysms treated with the Dolenc approach. All 17 cases of aneurysms were clipped successfully using the Dolenc approach, of which, 1 case with ipsilateral MCA occlusion underwent extracranial-intracranial artery bypass after the aneurysm clipping. Regarding clinical outcomes, six out of nine cases with preoperative visual impairment improved after surgery, two cases saw no change, and one case deteriorated. Of all the cases, one had new-onset vision loss, four had new-onset oculomotor paralysis, three had surgical side cerebral infarction, and two had diabetes insipidus. DSA or CTA examination within 2 weeks after surgery showed that all aneurysms were completely clipped without residual. After a follow-up of 9-12 months, 17 patients were evaluated based on GOS and CTA examination. A total of 14 cases had GOS 5 scores, 2 cases had GOS 4 scores, 1 case had GOS 2 scores, and no cases had death. None of the patients had recurrence based on CTA examinations. Through the Dolenc approach, we could achieve more operation space and expose clinoid segments for temporary occlusion. Therefore, the Dolenc approach was shown to be a safe, effective, and feasible treatment for giant C6-C7 aneurysms.

Health tracking media and the production of operational space: A critical analysis of Qantas Wellbeing App

This article examines the production of operational space amidst the rise of self- and data-tracking media, through the case study of the Qantas Wellbeing App. We draw on the operational paradigm in media studies to envisage how the Qantas Wellbeing App is embedded in the social-material relations between its users and the app, and the broader data-platform economy. By conceptualising the Qantas Wellbeing App as an operational media, the inquiry focuses on its designs and techniques that prompt users to fulfil prescribed tasks and follow instructions. We follow Lefebvre's conceptualisation of the production of space to evaluate three sets of social relations reconfigured by the Qantas Wellbeing App: human-to-human, human-to-machine, and data-to-data. By relying on qualitative evidence collected from an auto-ethnographic approach, our analyses focus on (1) spatial practices and (2) social relations constructed around the Qantas Wellbeing App between the authors to argue that social space is becoming a programmed reality that adheres to the logic of technological automation. Our analysis here affirms the app's capacity and objective to modify human behaviours and to evaluate how the app has recalibrated the authors’ respective and shared social spaces to create the needed condition of behaviour changes among the users. As social space is centred around human relations and activities, human agency and lives become secondary in an operational regime, which relies on data synchronisation to prosecute for the operational space and life.

A model-based approach towards accelerated process development: A case study on chromatography

Process development is typically associated with lengthy wet-lab experiments for the identification of good candidate setups and operating conditions. In this paper, we present the key features of a model-based approach for the identification and assessment of process design space (DSp), integrating the analysis of process performance and flexibility. The presented approach comprises three main steps: (1) model development & problem formulation, (2) DSp identification, and (3) DSp analysis. We demonstrate how such an approach can be used for the identification of acceptable operating spaces that enable the assessment of different operating points and quantification of process flexibility. The above steps are demonstrated on Protein A chromatographic purification of antibody-based therapeutics used in biopharmaceutical manufacturing.

Factors affecting airing in operational spaces in mines at Belaruskali

Factors affecting airing in operational spaces in mines at Belaruskali

Probabilistic surrogate-based optimization of ship hull-propulsor design with bi-level infill sampling technique

This work develops a new multi-level hull-propulsor optimization tool, systematically considering the full range of expected operating conditions. Different solvers with variable fidelities are used to evaluate hydrodynamic objective functions and constraints. The bi-fidelity surrogate model is applied to integrate the accuracy advantage of a medium-fidelity solver with the efficiency advantage of a low-fidelity solver. A bi-level technique of infill sampling integrated with a new version of multi-objective evolutionary algorithms is presented to enhance the effectiveness of the surrogate models. A ship velocity- and sea state-based joint probability density function is employed to take into account the real lifetime operational space. The well-known S175 containership, KP505 propeller and a MAN B&W marine engine are utilized as the initial hull-propulsor model. The final results show that the optimization framework is able to achieve some optimum hull-propulsor designs from the lifetime fuel consumption and energy efficiency design index points of view and to reduce the overall lifetime ownership cost significantly.

Space use in Central Business District of emerging economies: Regulation or rationale?

The Central Business District (CBD)[1] mimics a jungle where businesses and people compete for the best space and use because of its socioeconomic and political roles in a city. This zone attracts many users and uses, making it a focus of regulative planning, which is perceived as a useful behavioural control tool. However, whether a CBD's space user behaviour and use patterns are attributable solely to zoning guidelines and planning standards is not established. Using a case study design with Kumasi's CBD as the geographic scope, the study explored the patterns in space use within the lens of Ghana's Zoning Guidelines and Planning Standards and the factors informing user behaviour. The study found that space use in the CBD conforms extensively to the permissible activities enshrined in the guidelines, though open spaces and recreational parks are going extinct. However, some use prohibitions outlined in the Zoning Guidelines disconnect from reality and user rationality amid space use competitions. The study suggests that profit maximisation is the critical factor informing use patterns and user behaviour, aside factors like location, statutory demand, inheritance, social influence, and family decisions. The paper concludes that users’ subjective profit motives inform the user behaviour in CBDs of developing economies as against the perceived behavioural control embedded in guidelines and planning standards. It is recommended that attaining and maintaining inclusive and operative space use in the CBDs should integrate routine updating of regulatory frameworks and guidelines underpinned by rational choice models.[1] Central Business District.

Is India’s largest fertilizer manufacturer misleading farmers and society using dubious plant and soil science?

Background and AimsThe accessibility and relatively low cost of nitrogen (N) fertilizers have been a gift to humankind and made it possible to feed the exponentially growing world population. The excessive use of N, in combination with a poor N use efficiency (NUE) in crop production, is associated with severe environmental impacts, and the scientific community has repeatedly warned that the safe operating space for N within the planetary boundaries has been exceeded. In the light of these considerations, a global player and India’s largest fertilizer manufacturer, the Indian Farmers Fertilizer Cooperative (IFFCO), has recently developed and patented a nanotechnology-based fertilizer marketed as Nano Urea (liquid). Strikingly, the producers state that it is now possible to replace a 45 kg bag of conventional urea, containing 21 kg N, by foliar application of just 20 g N in the form of nano urea (NU). If so, N from this novel high-tech fertilizer product should be able to increase the NUE of crops more than 1000 times compared to conventional urea. This year, the Indian government and IFFCO announced plans to massively boost production by building 10 new factories, with an annual production capacity of 440 million bottles NU by 2025 and to expand export of the product to another 25 countries, mainly situated in Asia, Africa and South-America. In the marketing of NU, IFFCO states that there is scientific evidence for distinct beneficial properties in terms of higher crop yields and reduced negative environmental impacts. Similar ambitions have recently been presented for Nano Zinc, Nano Copper, and Nano Di-Ammonium-Phosphate, a product that entered the market in March 2023.MethodsIn this Opinion Paper, we compare the claims made by IFFCO scientists to the existing scientific evidence in the field of foliar nanofertilizers.ResultsWe observe that NU is a poorly described product with no scientifically proven effects. The product is marketed with misleading and wrong statements about its fertilizer efficiency, the underlying plant uptake pathways, and the environmental friendliness.ConclusionThe expectations raised by IFFCO are far from reality and may lead to large-scale yield losses with serious consequences for food security and the livelihood of farmers. At the same time, the confidence in innovative sustainable products as well as the science behind them may be threatened. Based on the IFFCO case, and considering the booming emergence of novel nano based fertilizers appearing all over the world these years, it is clear that much more priority should be given to scientifically prove their efficacy and mode of action, before they are launched on the markets.

An investigation into how space weather operational centre products meet end-user needs

Potential beneficiaries of the COSPAR Space Weather Roadmap can be classified in two groups – 1) operational space weather service providers, which can be viewed as direct users of the science developed through the COSPAR roadmap process; 2) end-users such as the electricity and satellites sectors whose requirements should define the metrics and parameters delivered through the products of space weather service providers, which therefore are intimately linked to the focus and evolution of the COSPAR roadmap.With regard to Group (1), interaction with COSPAR that feeds Group 2 requirements into the roadmap process may be enhanced via specific activities such as:•Participation in COSPAR bodies such as the Panel on Space Weather and ISWAT.•Participation in ISES and WMO space weather teams that are increasingly engaging with COSPAR to better coordinate research and operational space weather activities.•Promoting actions to ensure the R2O-O2R circle is complete - this may include adopting specific R2O-O2R actions or best-practice identified through WMO, ISES, or COSPAR activities that may also be effectively used to focus future iterations of COSPAR space weather roadmaps.Group 2 members often exist at one step further removed from the research community (i.e., they typically speak to operational service providers (Group (1) and these service providers interact with the research community), so there is a risk that their requirements are not fully addressed by the operational service providers and of a disconnect with the research community. To strengthen the research/operational centre/end-user chain, we first need to know how the operational centres and end-users interact, via a survey. Following this, we can better target research to support operational centres and understand how the research to end-user connections may be improved.In this paper, we describe such a survey and present the results. The survey focuses on the level of engagement between operational centres and end-users, end-user views of the quality of existing services, and their views on how further research can be exploited to better meet their requirements. We focus on the six key end-user sectors of Power, Aviation, Satellites, HF communications, GNSS, and Aurora Watchers. Via these examples, the connection from end-user impacts through to operations through to research requirements can be clarified. We further summarise the survey findings in terms of the end-user impact pathways defined in Schrijver et al. (2015).

Tipping in complex systems under fast variations of parameters

Abrupt changes in the state of a system are often undesirable in natural and human-made systems. Such transitions occurring due to fast variations of system parameters are called rate-induced tipping (R-tipping). While a quasi-steady or sufficiently slow variation of a parameter does not result in tipping, a continuous variation of the parameter at a rate greater than a critical rate results in tipping. Such R-tipping would be catastrophic in real-world systems. We experimentally demonstrate R-tipping in a real-world complex system and decipher its mechanism. There is a critical rate of change of parameter above which the system undergoes tipping. We discover that there is another system variable varying simultaneously at a timescale different from that of the driver (control parameter). The competition between the effects of processes at these two timescales determines if and when tipping occurs. Motivated by the experiments, we use a nonlinear oscillator model, exhibiting Hopf bifurcation, to generalize such type of tipping to complex systems where multiple comparable timescales compete to determine the dynamics. We also explain the advanced onset of tipping, which reveals that the safe operating space of the system reduces with the increase in the rate of variations of parameters.

Clinical efficacy of sclerotonyxis for acute angle-closure glaucoma with persistent high intraocular pressure.

The aim of the study was to investigate the clinical effectiveness and safety of sclerotonyxis in acute angle-closure glaucoma (ACG) with persistent high intraocular pressure (IOP). The clinical data of 50 eyes from 50 patients (mean age: 68.9±7.19 years) with acute ACG and persistently high IOP who were admitted to our department between January 2012 and January 2022 were retrospectively analyzed. Patients who were administered the maximum dose of systemic and topical anti-glaucoma drugs and still had an IOP of >40 mmHg 24 hours after admission underwent sclerotonyxis. After the IOP control, an individualized phase II treatment plan was designed according to the patient's ocular condition. Forty-eight patients showed improvement in their visual acuity 6 months postoperatively compared to their preoperative values. The mean IOPs were 54.84±7.82 mmHg and 21.34±7.81 mmHg 24 hours pre and postoperatively, respectively. The mean anterior chamber depth showed statistically significant differences pre and postoperatively (1.75±0.16 mm and 1.84±0.17 mm, respectively) (p<0.05). After IOP stabilized, four patients underwent YAG laser peripheral iridectomy, 18 underwent simple cataract phacoemulsification combined with intraocular lens (IOL) implantation, 21 underwent cataract phacoemulsification combined with IOL implantation and goniosynechialysis under a gonioscope, and 7 patients underwent combined surgery of glaucoma and cataract. The mean IOPs were 15.94±3.3 mmHg and 15.64±2.99 mmHg 1 week and 6 months after stage II surgery, respectively. Moreover, 42 eyes (84%) attained complete success and 8 eyes (16%) attained conditional success 6 months postoperatively. No serious complications, such as corneal endothelial decompensation, malignant glaucoma, vitreous or eruptive choroidal hemorrhage, and retinal detachment, were observed intraoperatively or postoperatively in both procedures. Sclerotonyxis can rapidly lower IOP, release the pupillary blockage, reconstruct the anterior chamber, and reduce systemic complications caused by long-term high-dose antiglaucoma drugs. Thus, it normalizes the IOP and provides a safe operating space for stage II surgery, effectively reducing complications in patients in a persistent high IOP state.

Conceptual Design of Artificial Intelligence Powered Automated Space Debris Remover (ASDR)

The focus of this research article is the application of AI technology for space debris removal. With the increasing number of non-functional artificial objects orbiting Earth, commonly known as space debris or junk, the need to address this issue has become crucial. Currently, there are over 200,000 such objects posing a significant threat to operational satellites and space missions. To mitigate this risk, we propose the utilization of AI-trained robotic systems to safely de-orbit space debris, thereby reducing the probability of collisions and potential damage. This research paper introduces the concept of employing AI and robotics technology to achieve this objective, with a specific emphasis on targeting Point Nemo as a designated disposal location. By harnessing the capabilities of AI, we can effectively identify and track space debris, enabling the robotic system to navigate and remove debris from critical orbital paths safely. Furthermore, the re-entry trajectory directed towards Point Nemo ensures that approximately 95% of the debris will burn up upon atmospheric re-entry, thus minimizing any potential risks to human life and property.

Relative Impact of Spacecraft Payload Mass Fraction on Spacecraft Operations and Lifespan

Spacecraft payloads are the sensing components that remain active over time and ensure Spacecraft's capability to perform multiple operations. It determines the rate of mission extension and the amount of scientific return based on extended performance. But it degrades over time due to the continuous process of operation and several space environmental factors. This paper has estimated payload mass fraction using the Spacecraft's data to relate it to the lifetime of orbital Spacecraft. Our prime intent is to check whether the spacecraft payload mass fraction affects the Spacecraft's lifetime concerning the initial hypothesis that the spacecraft mass greatly influences spacecraft lifetime. We derive some mathematical relation and establish a relationship between spacecraft payload mass fraction and lifetime. Finally, to verify our relation, we employ spacecraft data to investigate and interpret reliability behavior based on payload fraction and lifetime relation.

Misalignment tolerance improvement and high efficiency design for wireless power transfer system based on DDQ‐DD coil

SummaryThis paper addresses misalignment tolerance improvement and high‐efficiency maintenance for wireless power transmission systems. Firstly, a receiving coil is designed according to Standard J2954, published by the Society of Automotive Engineers. Next, a DDQ transmitting coil is designed to accommodate a constrained operating space. The structure and parameters of the transmitting coils are determined to obtain a high coupling coefficient when offset occurs. Subsequently, an analysis is carried out to determine the relationship between the coupler magnetic fields and power transmission ability. A current phase control strategy is developed to deal with the mismatched magnetic fields, and a switching threshold is selected to obtain high power transmission efficiency. Finally, an experimental system is set up using the designed coil. The experimental results demonstrate that the system can maintain high efficiency even when lateral misalignment occurs in different directions. A maximum transmission efficiency of 89.63% is obtained, which validates the effectiveness of the proposed method.

Experimental investigation on bolted inter-module connections and subassemblies of steel modular frames

Modular construction, which involves prefabricating free-standing modules in a factory and assembling them on site to form a building, is gaining popularity worldwide. However, the existing inter-module connections generally require additional operation space and present difficulties in aligning adjacent modules quickly. Additionally, the global behavior of modular frames with inter-module connections under lateral loading is not well understood. To address these issues, this study investigates two types of inter-module connections (referred to as Type A and Type B), with high buildability and self-aligning features. Five pull-out tests were conducted to study the tensile behavior of the two types of inter-module connections, and five subassemblies of modular frames with these two types of inter-module connections were tested to study their global behavior under lateral loading. Based on the test results, the yielding distribution and development, strength, ductility, and failure modes were discussed for both types of inter-module connections under tensile loading and for the modular frames under lateral loading. Yielding of the steel plate (the end plate or anchoring plate), as anticipated, is found to be preferable to bolt failure for both types of inter-module connections to achieve greater ductility under tensile loading. Premature fracture of the beam-to-column weld was identified as the main failure mode for all tested subassemblies of modular frames. As this early weld fracture prevented further development of both strength and deformation of the modular frame, it is recommended to avoid this failure mode in the design of modular frames.