Watt Linkage–Based Legged Deployable Landing Mechanism for Reusable Launch Vehicle: Principle, Prototype Design, and Experimental Validation

The reusable launch vehicle (RLV) presents a new avenue for reducing cost of space transportation. The landing mechanism, which provides landing support and impact absorption, is a vital component of the RLV at final stage of recovery. This study proposes a novel legged deployable landing mechanism (LDLM) for RLV. The Watt-II six-bar mechanism is adopted to obtain the preferred configuration via the application of the linkage variation approach. To endow the proposed LDLM with advantages of large landing support region, lightweight, and reasonable linkage internal forces, a multi-objective optimization paradigm is developed. Furthermore, the optimal scale parameters for guiding the LDLM prototype design is obtained numerically using the non-dominated sorting genetic algorithm-II (NSGA-II) evolutionary algorithm. A fully-functional scaled RLV prototype is developed by integrating the gravity-governed deploying scheme to facilitate unfolding action to avoid full-range actuation, a dual-backup locking mechanism to enhance reliability of structure stiffening as fully deployed, and a shock absorber (SA) with multistage honeycomb to offer reliable shock absorbing performance. The experimental results demonstrate that the proposed LDLM is capable of providing rapid and smooth deployment (duration less than 1.5 s) with mild posture disturbance to the cabin (yaw and pitch fluctuations less than 6°). In addition, it provides satisfactory impact attenuation (acceleration peak less than 10g (g is the gravitational acceleration)) in the 0.2 m freefall test, which makes the proposed LDLM a potential alternative for developing future RLV archetype.

Reusable Component Technology in the Development of Agile Supply Chain Management System

Agile Supply Chain Management (ASCM) is one of the ke y techniques, which support dynamic enterprise alliance and realize agile manufa cturing. But the optimal run of ASCS depends on a good-constructed Agile Supply Chain Management System (ASCMS), so that the materials flow, information flow a nd funding flow in the supply chain are used with high efficiency. The requireme nts of ASCMS are constantly changeable, which requires that ASCMS has dynamical reuse, integration and open interface. Reusable components theory is one of the most important directions of software engineering. It’s a feasible approach to solve software crisis and to increase software productivity and quality. ASCMS d eveloped with reusable components can easily be re-constructed, and has good op en interfaces. It will also sharply shorten the development life circle of syste m, and avoid unnecessary errors that result from the process of re-developing t hose components. In order to develop ASCMS based on reusable components quickly, the first thing we need to do is to construct the framework for ASCMS called system architecture . The framework referred in this context is not only a reference system of ASCMS , but also the operation system (including run-time library and communication p rotocols), which the ASCMS determined. So we can abstract logic units of the sys tem (they are the logic base of the ASCMS components), and the relationships amo ng them. And the operation system and communication protocols provide these comp onents with a running platform. Of course, the most important thing is to constr uct an abundant components depository. Components in the depository should h ave some properties such as: (1) Components should be built upon a specific oper ation system (e.g., windows) and standard communication protocols (e.g., IIOP in CORBA’s specification); (2)Self-containment, that shows it’s unnecessary to include other components when some component is reused since that component cont ains the needed relevant components in itself; (3) Identification, components ha ve to be clearly identifiable, that shows components are contained in a file rat her than spread over other systems and intermixed with other modules of soft ware; (4) Functionality, that shows components have a clearly specified function ality; (5)Open interface; (6) Comprehensive and brief documentation Moreover, it ’s necessary to classify these components properly so as to manage the deposito ry efficiently. Thus in this paper, we will firstly describe in detail the basic reusable model of SCMS and also the properties and depiction methods of business objects an d business components in SCMS. And then we will establish the 5-layer model of business components in SCMS and discuss the methods to get and store the reusabl e components. Based on those introduced, we will provide an assembling method fo r the constructing of SCMS, making use of component technology and an applicatio n is presented.

Efficient heavy metal recycling and water reuse from industrial wastewater using new reusable and inexpensive polyphenylene sulfide derivatives

Heavy metal(HM)pollution is a serious environment problem.Recovering HM from industrial wastewater by efficient adsorbents is a sustainable method due to recycling HM and acquiring reusable water.However,popular efficient adsorbents are usually expensive or non-reusable.In this paper,methods of efficient HM recycling and water reuse from industrial wastewater were developed using efficient adsorbents,new polyphenylene sulfide derivatives,which are recyclable and stable in an acidic,alkaline or oxidative aqueous solution.Moreover,they can efficiently and quickly adsorb HM ions.The maximum adsorption capacities of these adsorbents for HM ions are at the range from 51.3-184.2 mg·g^(-1).The adsorption equilibrium times of them for HM ions are at the range from 10 to 80 min.Therefore,this paper suggests sustainable methods of HM recovery and water reuse from industrial wastewater.

A Footpad Structure with Reusable Energy Absorption Capability for Deep Space Exploration Lander:Design and Analysis

The footpad structure of a deep space exploration lander is a critical system that makes the initial contact with the ground,and thereby plays a crucial role in determining the stability and energy absorption characteristics during the impact process.The conventional footpad is typically designed with an aluminum honeycomb structure that dissipates energy through plastic deformation.Nevertheless,its effectiveness in providing cushioning and energy absorption becomes significantly compromised when the structure is crushed,rendering it unusable for reusable landers in the future.This study presents a methodology for designing and evaluating structural energy absorption systems incorporating recoverable strain constraints of shape memory alloys(SMA).The topological configuration of the energy absorbing structure is derived using an equivalent static load method(ESL),and three lightweight footpad designs featuring honeycomb-like Ni-Ti shape memory alloys structures and having variable stiffness skins are proposed.To verify the accuracy of the numerical modelling,a honeycomb-like structure subjected to compression load is modeled and then compared with experimental results.Moreover,the influence of the configurations and thickness distribution of the proposed structures on their energy absorption performance is comprehensively evaluated using finite element simulations.The results demonstrate that the proposed design approach effectively regulates the strain threshold to maintain the SMA within the constraint of maximum recoverable strain,resulting in a structural energy absorption capacity of 362 J/kg with a crushing force efficiency greater than 63%.

Robust and Reusable Fuzzy Extractors from Non-Uniform Learning with Errors Problem

Afuzzy extractor can extract an almost uniformrandom string from a noisy source with enough entropy such as biometric data.To reproduce an identical key from repeated readings of biometric data,the fuzzy extractor generates a helper data and a random string from biometric data and uses the helper data to reproduce the random string from the second reading.In 2013,Fuller et al.proposed a computational fuzzy extractor based on the learning with errors problem.Their construction,however,can tolerate a sub-linear fraction of errors and has an inefficient decoding algorithm,which causes the reproducing time to increase significantly.In 2016,Canetti et al.proposed a fuzzy extractor with inputs from low-entropy distributions based on a strong primitive,which is called digital locker.However,their construction necessitates an excessive amount of storage space for the helper data,which is stored in authentication server.Based on these observations,we propose a new efficient computational fuzzy extractorwith small size of helper data.Our scheme supports reusability and robustness,which are security notions that must be satisfied in order to use a fuzzy extractor as a secure authentication method in real life.Also,it conceals no information about the biometric data and thanks to the new decoding algorithm can tolerate linear errors.Based on the non-uniform learning with errors problem,we present a formal security proof for the proposed fuzzy extractor.Furthermore,we analyze the performance of our fuzzy extractor scheme and provide parameter sets that meet the security requirements.As a result of our implementation and analysis,we show that our scheme outperforms previous fuzzy extractor schemes in terms of the efficiency of the generation and reproduction algorithms,as well as the size of helper data.

Artificial Intelligence Model for Software Reusability Prediction System

The most significant invention made in recent years to serve various applications is software.Developing a faultless software system requires the soft-ware system design to be resilient.To make the software design more efficient,it is essential to assess the reusability of the components used.This paper proposes a software reusability prediction model named Flexible Random Fit(FRF)based on aging resilience for a Service Net(SN)software system.The reusability predic-tion model is developed based on a multilevel optimization technique based on software characteristics such as cohesion,coupling,and complexity.Metrics are obtained from the SN software system,which is then subjected to min-max nor-malization to avoid any saturation during the learning process.The feature extrac-tion process is made more feasible by enriching the data quality via outlier detection.The reusability of the classes is estimated based on a tool called Soft Audit.Software reusability can be predicted more effectively based on the pro-posed FRF-ANN(Flexible Random Fit-Artificial Neural Network)algorithm.Performance evaluation shows that the proposed algorithm outperforms all the other techniques,thus ensuring the optimization of software reusability based on aging resilient.The model is then tested using constraint-based testing techni-ques to make sure that it is perfect at optimizing and making predictions.

Towards cultivar-oriented gene discovery for better crops

The continued expansion of the world population,increasingly inconsistent climate and shrinking agricultural resources present major challenges to crop breeding.Fortunately,the increasing ability to discover and manipulate genes creates new opportunities to develop more productive and resilient cultivars.Many genes have been described in papers as being beneficial for yield increase.However,few of them have been translated into increased yield on farms.In contrast,commercial breeders are facing gene decidophobia,i.e.,puzzled about which gene to choose for breeding among the many identified,a huge chasm between gene discovery and cultivar innovation.The purpose of this paper is to draw attention to the shortfalls in current gene discovery research and to emphasise the need to align with cultivar innovation.The methodology dictates that genetic studies not only focus on gene discovery but also pay good attention to the genetic backgrounds,experimental validation in relevant environments,appropriate crop management,and data reusability.The close of the gaps should accelerate the application of molecular study in breeding and contribute to future global food security.

Biocatalytic enhancement of laccase immobilized on ZnFe_(2)O_(4) nanoparticles and its application for degradation of textile dyes

Efficient and convenient treatment of industrial dyeing wastewater is of great significance to guarantee human and animal health.This work presented the enhanced catalytic activity at pH 3.0 of laccase immobilized on amino-functionalized ZnFe_(2)O_(4) nanoparticles(ZnFe_(2)O_(4)-laccase)and its application for the degradation of textile dyes.Due to the existence of a large number of oxygen vacancies on the surface of the ZnFe_(2)O_(4) nanoparticles,negative ions accumulated on the magnetic carriers,which resulted in a harsh optimal pH value of the ZnFe_(2)O_(4)-laccase.Laccase activity assays revealed that the ZnFe_(2)O_(4)-laccase possessed superior pH and thermal stabilities,excellent reusability,and noticeable organic solvent tolerance.Meanwhile,the ZnFe_(2)O_(4) laccase presented efficient and sustainable degradation of high concentrations of textile dyes.The initial decoloration efficiencies of malachite green(MG),brilliant green(BG),azophloxine,crystal violet(CV),reactive blue 19(RB19),and procion red MX-5B were approximately 99.1%,95.0%,93.3%,87.4%,86.1%,and 85.3%,respectively.After 10 consecutive reuses,the degradation rates of the textile dyes still maintained about 98.2%,92.5%,83.2%,81.5%,79.8%and 65.9%,respectively.The excellent dye degradation properties indicate that the ZnFe_(2)O_(4)-laccase has a technical application in high concentrations of dyestuff treatment.

Superwetting Ag/α-Fe_(2)O_(3) anchored mesh with enhanced photocatalytic and antibacterial activities for efficient water purification

Superwetting materials have drawn unprecedented attention in the treatment of oily wastewater due to their preferable anti-fouling property and selective oil/water separation.However,it is still a challenge to fabricate multifunctional and environmentally friendly materials,which can be stably applied to purify the actual complicated wastewater.Here,a Ag/Ag/α-Fe_(2)O_(3) heterostructure anchored copper mesh was intentionally synthesized using a facile two-step hydrothermal method.The resultant mesh with superhydrophilicity and underwater superoleophobicity was capable of separating various oil/water mixtures with superior separation efficiency and high permeationflux driven by gravity.Benefiting from the joint effects of the smaller band gap of Ag/α-Fe_(2)O_(3) heterojunction,inherent antibacterial capacity of Ag/α-Fe_(2)O_(3) and Ag nanoparticles,favorable conductive substrate,as well as the hierarchical structure with superwettability,such mesh presented remarkably enhanced degradation capability toward organic dyes under visible light irradiation and antibacterial activity against both Escherichia coli(E.coli)and Staphylococcus aureus(S.aureus)compared with the pure Ag/α-Fe_(2)O_(3) coated mesh.Impressively,the mesh exhibited bifunctional water purification performance,in which organic dyes were eliminated simultaneously from water during oil/water separation in onefiltration process.More importantly,this mesh behaved exceptional chemical resistance,mechanical stability and long-term reusability.Therefore,this material with multifunctional integration may hold promising potential for steady water purification in practice.

Leveraging React Components in Business Process Management (BPM) Applications

As organizations increasingly embrace digital transformation, the integration of modern web technologies like React.js with Business Process Management (BPM) applications has become essential. React components offer flexibility, reusability, and scalability, making them ideal for enhancing user interfaces and driving user engagement within BPM environments. This article explores the benefits, challenges, and best practices of leveraging React components in BPM applications, along with real-world examples of successful implementations.

An Overview of Bearing Candidates for the Next Generation of Reusable Liquid Rocket Turbopumps

There is a consensus in the aerospace field that the development of reusable liquid rockets can effectively reduce the launch expense.The pursuit of a long service life and reutilization highly depends on the bearing components.However,the rolling element bearings(REBs)used in the existing rocket turbopumps present obvious and increasing limitations due to their mechanical contacting mode.For REBs,high rotational speed and long service life are two performance indexes that mutually restrict each other.To go beyond the DN value(the product of the bearing bore and rotational speed)limit of REBs,the major space powers have conducted substantial explorations on the use of new types of bearings to replace the REB.This review discusses,first,the crucial role of bearings in rocket turbopumps and the related structural improvements of REBs.Then,with the prospect of application to the next generation of reusable liquid rocket turbopumps,the bearing candidates investigated by major space powers are summarized comprehensively.These promising alternatives to REBs include fluid-film,foil,and magnetic bearings,together with the novel superconducting compound bearings recently proposed by our team.Our more than ten years of relevant research on fluid-film and magnetic bearings are also introduced.This review is meaningful for the development of long-life and highly reliable bearings to be used in future reusable rocket turbopumps.

Robust Attitude Control for Reusable Launch Vehicles Based on Fractional Calculus and Pigeon-inspired Optimization

In this paper, a robust attitude control system based on fractional order sliding mode control and dynamic inversion approach is presented for the reusable launch vehicle(RLV)during the reentry phase. By introducing the fractional order sliding surface to replace the integer order one, we design robust outer loop controller to compensate the error introduced by inner loop controller designed by dynamic inversion approach. To take the uncertainties of aerodynamic parameters into account,stochastic robustness design approach based on the Monte Carlo simulation and Pigeon-inspired optimization is established to increase the robustness of the controller. Some simulation results are given out which indicate the reliability and effectiveness of the attitude control system.

Covalently anchored sulfonic acid on silica gel(SiO_2-R-SO_3H)as an efficient and reusable heterogeneous catalyst for the one-pot synthesis of 1,8-dioxooctahydroxanthenes under solvent-free conditions

A highly efficient one-pot synthesis of 1,8-dioxooctahydroxanthenes under solvent-free conditions catalyzed by sulfonic acid covalently anchored onto the surface of silica gel is reported. All types of aldehydes, including aromatic, unsaturated, and heterocyclic, are used. The silica gel/sulfonic acid catalyst （SiO2-R-SO3H） is completely heterogeneous and can be recycled.

Hierarchical structured robust adaptive attitude controller design for reusable launch vehicles

Reentry attitude control for reusable launch vehicles （RLVs） is challenging due to the characters of fast nonlinear dy- namics and large flight envelop. A hierarchical structured attitude control system for an RLV is proposed and an unpowered RLV con- trol model is developed. Then, the hierarchical structured control frame consisting of attitude controller, compound control strategy and control allocation is presented. At the core of the design is a robust adaptive control （RAC） law based on dual loop time-scale separation. A radial basis function neural network （RBFNN） is implemented for compensation of uncertain model dynamics and external disturbances in the inner loop. And then the robust op- timization is applied in the outer loop to guarantee performance robustness. The overall control design frame retains the simplicity in design while simultaneously assuring the adaptive and robust performance. The hierarchical structured robust adaptive con- troller （HSRAC） incorporates flexibility into the design with regard to controller versatility to various reentry mission requirements. Simulation results show that the improved tracking performance is achieved by means of RAC.

Six-DOF trajectory optimization for reusable launch vehicles via Gauss pseudospectral method

To be close to the practical flight process and increase the precision of optimal trajectory, a six-degree-offreedom（6-DOF） trajectory is optimized for the reusable launch vehicle（RLV） using the Gauss pseudospectral method（GPM）. Different from the traditional trajectory optimization problem which generally considers the RLV as a point mass, the coupling between translational dynamics and rotational dynamics is taken into account. An optimization problem is formulated to minimize a performance index subject to 6-DOF equations of motion, including translational and rotational dynamics. A two-step optimal strategy is then introduced to reduce the large calculations caused by multiple variables and convergence confinement in 6-DOF trajectory optimization. The simulation results demonstrate that the 6-DOF trajectory optimal strategy for RLV is feasible.

OPEN ARCHITECTURE FOR INTERNET BASED TELE-ROBOTIC SYSTEM

Building an Internet based tele-robotic system requires the developers beingproficient in computer theory, network technology, control theory, etc. A flexible, open structuredand module based framework for tele-control system is proposed on the basis of abstraction andanalysis of existing Internet-based control systems. This framework is designed following the peerto peer (P2P) distributed computing model. As a key to the system, the XML based ontology ofresources/modules/peers is discussed, so do the model for dynamically allocating of resources, basedon which the coordination among modules or peers can then be implemented. The experiment system andits experimental results prove the feasibility of the framework and its ease to use.

Fabrication of a High-Performance and Reusable Planar Face Mask in Response to the COVID-19 Pandemic

The coronavirus disease 2019(COVID-19)pandemic has caused a surge in demand for face masks,with the massive consumption of masks leading to an increase in resource-related and environmental con-cerns.In this work,we fabricated meltblown polypropylene(mb-PP)-based high-performance planar face masks and investigated the effects of six commonly used disinfection methods and various mask-wearing periods on the reusability of these masks.The results show that,after three cycles of treatment using hot water at 70℃ for 30 min,which is one of the most scalable,user-friendly methods for viral disinfection,the particle filtration efficiency(PFE)of the mask remained almost unchanged.After mask wearing for 24 h and subsequent disinfection using the same treatment procedures,the PFE decreased to 91.3%;the average number of bacterial and fungal colonies was assessed to be 9.2 and 51.6 colony-forming units per gram(CFU∙g^(-1)),respectively;and coliform and pyogenic bacteria were not detected.Both the PFE and the microbial indicators are well above the standard for reusable masks after disinfection.Schlieren pho-tography was then used to assess the capabilities of used and disinfected masks during use;it showed that the masks exhibit a high performance in suppressing the spread of breathed air.

Representation and Adaptive Transformation of Reusable Software Components

The key ingredient for promoting software reuse in a repository base integrated development environment, is to provide support for the software developer who wants to search the repository to locate and retrieve suitable software components for reuse. This paper presents that reusable software components form a base to provide a flexible representation of component adaptability to any repository with a specific classification. As an alternative, it proposes to automatically identify and convert the component source code with all its information into a standard form, so that components can be transferred from one type of library to another.

A new free recoverable and reusable mono-alkaloid-type ligand and its use in preparation of ethyl(2R,3S)-2,3-dihydroxy-3-phenylpropionate

A new free recoverable and reusable mono-alkaloid-type ligand has been synthesized by a simple method. With highly polar groups, the ligand can be recycled and reused eight times to prepare ethyl （2R,3S）-2,3-dihydroxy-3-phenylpropionate with high yield and ee via asymmetric dihydroxylation （AD） reaction. C 2009 Sheng Yong Zhang. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

CORBA-Based Discrete Event Simulation System

The CORBA technique is an integration of the object-oriented conception and distributed computing technique. It can make the application within distributed heterogeneous environments reusable, portable and interoperable. The architecture of CORBA-based discrete event simulation systems is presented and the interface of distributed simulation objects (DSO) is defined in this paper after the DSO is identified and the synchronization mechanism among DSO is discussed.