Fabricating a bonded magnet with a near-net shape in suitable thermoplastic polymer binders is of paramount importance in the development of cost-effective energy technologies. In this work, anisotropic Sm2Fe17N3 (Sm-Fe-N) bonded magnets are additively printed using Sm-Fe-N anisotropic magnetic particles in a polymeric binder polyamide-12 (PA12). The anisotropic bonded permanent magnets are fabricated by Big Area Additive Manufacturing followed by post-aligned in a magnetic field. Optimal post-alignment results in an enhanced remanence of ~ 0.68 T in PA12 reflected in a parallel-oriented (aligned) measured direction. The maximum energy product achieved for the additively printed anisotropic bonded magnet of Sm-Fe-N in PA12 polymer is 78.8 KJ m-3. Our results show advanced processing flexibility of additive manufacturing for the development of Sm-Fe-N bonded magnets in polymer media designed for applications with no critical rare earth magnets.

Stent migration due to haemodynamic drag remains the primary cause of type I endoleak, potentially leading to aneurysm rupture. The prevalence of migration and endoleak can be partially attributed to deficiencies in stent-graft radial spring design and a lack in understanding of the mechanical properties of endovascular stents. A converged finite element model of a custom radial extensometer was developed, fit, and validated using experimental results for bare stent wire (”uncovered”) with outer diameter of 12 mm stent. During stent constriction to 50 % of the original cross- sectional area, a comparison of experimental and modeled results produced an r2 value of 0.946, a standard error of 0.099 N, and a mean percent error of 1.69 %. This validated finite element model can be used to analyze the mechanisms responsible for radial force generation in 316L stainless steel self-expanding endovascular stents, as well as to evaluate new stent designs.

The Linear Wireless Ad-Hoc Network (Linear WANET), as a branch of the Ad-Hoc network, refers to a self-organizing multi-hop wireless network in which nodes are arranged linearly. Frame aggregation and RTS/CTS schemes are introduced in IEEE 802.11 aims to improve network transmission performance. However, the traditional mechanisms may not have good adaptability in linear multi-hop networks. Thus, we defined a Linear WANET simulation model based on the IEEE 802.11 protocol. We established this model on the NS-3 network simulator to perform A-MSDU, A-MPDU, and two-level frame aggregation simulation and analyzed the aggregation performance under different channel environments. Meanwhile, the RTS/CTS and TXOP mechanisms were also simulated in this paper. We analyzed the performance of each mechanism in a Linear WANET under saturated and unsaturated environments. We found that in a Linear WANET, the A-MSDU mechanism can improve system performance to a limited extent, but at the same time, it will increase the packet loss rate and delay. Although the A-MPDU mechanism can reduce the retransmission overhead, the higher A-MPDU Limit cannot further improve the throughput of the Linear WANET. Meanwhile, in the case of single A-MPDU aggregation, there has a lowest data delivery interval that the Linear WANET system can withstand. Besides, we also found that the native TXOP mechanism cannot effectively improve the system efficiency of Linear WANET. And the RTS/CTS mechanism can improve the performance of Linear WANETs, especially in a saturated throughput environment.

Ricinodendron heudelotii, Vitex doniana and Cleome gynandra are three indigenous species of Benin/West Africa. This review focuses on the physicochemical characteristics of their seeds and the nutritional and functional properties of their oils. In this systematic review, scientific articles and reports were used to collect information. The minima, maxima and mean values were considered and converted into a dry basis and/or the same units by using the international system of units when needed to allow comparison. Seeds of Ricinodendron, Vitex and Cleome fat contents were 51.83 g/100 g dw, 28.55 g/100 g dw and 27.35 g/100 g dw, respectively. The three seed oils contained 58.54 to 87% mono and polyunsaturated fatty acids. Ricinodendron seed oil contained a conjugated polyunsaturated fatty acid α-eleostearic acid (49.3–51.1%). Data varied from one author to another due to the methods used. R. heudelotii seeds oil is traditionally used for the treatment of several diseases. Its oil showed phytochemical and antimicrobial properties suggesting its possible use in pharmaceutical industries. Ricinodendron and Vitex seed oil should not be used for cooking at high temperatures or frying because of their high and medium levels of unsaturation.

Due to the technical barriers between radars and jammers and the poor performance of the traditional detection-jamming shared signal in integrated radar-electronic warfare systems, a new detection-jamming shared signal waveform based on the virtual force field algorithm (VFFA) is proposed in this paper. First, a multi-objective and multi-dimensional characteristic parameter optimization model, based on a virtual force field, is established, and then the design principle of the shared signal is presented in detail. The simulation results show that the detection-jamming shared signal based on the VFFA presents the deceptive jamming of multiple false targets in non-collaborative radar. Further, there is better detection performance with the advantages of multiple pulse repetition frequency (PRF) and pulse accumulation number, which are highly sensitive to the multi-jagged PRF signals emitted by the non-collaborative radar. According to the VFFA described in this paper, the optimum detection-jamming shared signal waveform can be output in real time for specific free space targets, to improve the efficiency of integrated radar and electronic warfare systems.

The characterization of steel fiber concrete in a flexural test or tensile uniaxial test requires greater control of loading rate by the speed applied in the testmachine, to be able to report more accurately the behavior of displacementsor crack openings in micro-scale possible. In general, in the pre-dimensioningprocess, it is often discarded the characterization tests and the main standardsdo not provide theoretical design recommendations concerning the residualstrengths of fibrous concrete. Some empirical models in the literature attempt anapproximation of the theoretical design values, but they present greater dispersion in the results. This article proposes empirical equations for predicting theresidual strengths of the steel fiber reinforced concrete (SFRC), for small fibervolume fractions (approx. < 0.8%). Experimentally notched beams subjected tothree-point bending tests were collected, with the concrete matrix composed ofhook-end steel fiber and the experimental residual strengths presenting the softening behavior in the load-opening ratio curve of the crack. The experimentalresidual strengths were compared with other empirical models found in the literature. The results showed that the maximum stress of the steel fiber pulloutmodel established satisfactory relationships with the residual stresses in flexure.The empirical proposed residual strength model presented lower variability ofdispersion around 10%, the mean absolute percentage error of 8%, compared toother usual empirical models and had the same material class with the experimental results, proving to be a viable alternative for pre-design and dosageoptimization for SFRC.

Electricity is an important part of our daily life and uses for different purposes. However, electricity generation sources are decreasing day by day and electricity mainly generates from renewable and conventional sources of energy. Proper management to create new conventional energy sources is challenging all over the world. Lack of conventional sources of energy, high demand for energy, less available land, and low budget for energy are some of the important factors that cause poor energy management all over the world. In this paper, different potential less attributed sources of energy are analyzed along with their implementation techniques to mitigate high electricity demand in near-future. This review shows that along with renewable and conventional sources of energy, less attended energy sources would be a potential source that can generate electricity. This review also presents that no improved techniques are needed to implement less attended sources of energy and can be implemented with sustainable techniques. This study also proposes implementation techniques of uncommon sources of energy for electricity generation with related challenges that could emerge during the implementation of these sources of energy. In this study, the electricity generation rate and their corresponding applications are also depicted. Proper steps and execution of less attended sources of energy would mitigate high energy demand all over the world and offers a cleaner environment for livelihood.

The comprehensive fire and explosion risk assessment has been studied for Coal Reclaim Tunnel (CRT) facility by applying the Monte Carlo simulation method. In this research, the fire and explosion risk of two existing CRT, namely model A and model B, have been assessed. A set of 30 data for each factor has been used to define the statistical distribution model, sourced from historical data, field measurement, and laboratory experiments. Based on the simulation, CRT model A has a 100% extreme risk group, while model B has two risk groups, high risk=81.73% and moderate risk=18.27%, classified as a not acceptable risk. Several preventive actions were set to reduce the probability and severity level as low as reasonably possible, especially for the controllable factors. Furthermore, the probability and severity levels were re-adjusted by the Monte Carlo simulation. The result shows that both the CRT model have been grouped into a 100% moderate-risk group. For optimal prevention against explosion risk, a sensitivity analysis has been carried out to find the most influential factors for the fire and explosion risk in CRT. Through this research, a method for risk matrix assessment related to the fire and explosion in the CRT facility has been developed.

In the present paper, we determine the chemical equilibrium compositions for two combustion reactions involving either hydrazine or propane at fixed high pressure and temperature values using several computational approaches. Then, we compute the chemical equilibria for reacting systems under a multitude of temperature and pressure conditions and various initial system compositions. These sensitivity analyses are based on a combination of the method of Lagrangian multipliers and the arc-length continuation technique. Indeed, three industrially relevant case studies are elucidated: (1) the synthesis of ammonia using the Haber process, (2) the gasification of a typical biomass surrogate: glucose using steam and (3) the gasification of cellulose using steam. For all the above reacting systems, our results are benchmarked against their counterparts obtained either from the ubiquitous process simulator: ASPEN-Plus® or from data available in the open literature.

This study aims to investigate the effect of the processing parameters in plasma electrolytic oxidation (PEO) on the corrosion resistance of magnesium alloy type AZ91. The PEO coatings were prepared on the samples using alkaline-based electrolyte. Both unipolar and bipolar, different frequencies and duty cycles were applied. Corrosion tests, using potentiodynamic polarisation (PDP), linear and cyclic, and electrochemical impedance spectroscopy (EIS) techniques, were applied on the as-received and PEO coated samples. Scanning electron microscopy was used to investigate the surface morphology, e.g. micropores, as well as to measure the thickness of the coated layer with changing the processing parameters. The results show that the size of micropores is interrelated to the duty cycle percentage and current polarities, as the higher frequency causes thinner coating layers, with fewer micropores, consequently higher corrosion resistance. In addition, increasing the duty cycle, a denser and more compact coating was obtained. The XRD results showed missing peak of the α-Mg phase in a PEO coated sample using Bipolar, the highest frequency (1666 Hz) and the highest duty cycle (66.6%). The mils per year calculations showed that the PEO coated have lower corrosion rate by at least 8 times than the as-received alloy.

The biotechnological production of glycosides is an economically competitive manufacturing alternative to classical chemical synthesis. Through continuous production improvement, glycosides can now be used in low-cost products by various industries. However, many production systems still suffer from low yields. Directed evolution, coupled with a suitable screening method, can tackle this challenge. We generated glycosyltransferase mutants through error-prone-PCR and screened the library using a small-scale whole-cell biotransformation system. The screening of only 176 colonies yielded three putative candidates. Detailed investigations revealed that the reason for the increase in product titer was mainly due to different expression effects of the mutagenized genes rather than improved enzyme kinetics. In total, a 60-fold increase in product formation was achieved. Therefore, in addition to the quality of the mutant library, an efficient and stable expression system is crucial to achieve high concentrations of active enzyme and product, as formation of inclusion bodies and other inactive forms of the biocatalyst reduces productivity.

The Q/V band communication systems open new avenues for next generation of High Throughput Satellite (HTS) systems. More specifically, they are attractive due to their high bandwidth for user and gateway links. Having a wide bandwidth at Q/V band makes it permissible to offload the links between the satellite and its earth station hubs (gateway) from the Ka band to the Q/V band. This enables additional bandwidth available for HTS feeder links and user links of specific market verticals, which in turn results in reduction of cost per bit. In this paper, we are going to discuss different aspects of an In-Flight Connectivity (IFC) scheme for HTS. Developing a wideband and multibeam antenna is an essential part of this proposed system, which is also going to be discussed in this paper.

Through Silicon Via (TSV) technology is a key technology to realize multi-layer chips and its structure model and transmission characteristics have attracted much attention. With the continuous reduction of chip size, higher requirements are put forward for the model and transmission characteristics of TSV. A novel elliptic cylindrical TSV structure model is proposed. The influence of axial length ratio, height, dielectric layer thickness and spacing on the transmission characteristics of TSV are further studied by HFSS software. The results show that the transmission of TSV is facilitated by the decrease of axial length ratio, the decrease of height, the increase of dielectric layer thickness and the increase of TSV spacing. The TSV structural parameter values are optimized by a single variable method. The optimized TSV structure is compared with the original TSV, traditional cylindrical and conical TSV and coaxial TSV. It is concluded that the elliptic cylindrical TSV structure has better transmission performance. The temperature characteristics of the elliptic cylindrical TSV are simulated. It is indicated that the transmission characteristics of the elliptic cylindrical TSV are poor at low frequency and better at high frequency when the temperature rises.

Small-to-medium businesses are always seeking affordable ways to advertise their products and services securely. With the emergence of mobile technology, it is possible than ever to implement innovative Location-based Advertising (LBS) systems using smartphones that preserve the privacy of mobile users. In this paper, we present a prototype implementation of such systems by developing a distributed privacy-preserving system, which has parts executing on smartphones as a mobile app, as well as a web-based application hosted on the cloud. The mobile app leverages Google Maps libraries to enhance the user experience in using the app. Mobile users can use the app to commute to their daily destinations while viewing relevant ads such as job openings in their neighborhood, discounts on favorite meals, etc. We developed a client-server privacy architecture that anonymizes the mobile user trajectories using a bounded perturbation strategy. A multi-modal sensing approach is proposed for modeling the context switching of the developed LBS system, which we represent as a Finite State Machine (FSM) model. The multi-modal sensing approach can reduce the power consumed by mobile devices by automatically detecting sensing mode changes to avoid unnecessary sensing. The developed LBS system is organized into two parts: the business side and the user side. First, the business side allows business owners to create new ads by providing the ad details, Geo-location, photos, and any other instructions. Second, the user side allows mobile users to navigate through the map to see ads while walking, driving, bicycling, or quietly sitting in their offices. Experimental results are presented to demonstrate the scalability and performance of the mobile side. Our experimental evaluation demonstrates that the mobile app incurs low processing overhead and consequently has a small energy footprint.

A document by Minggang DU. Click on the document to view its contents.

A bendable UHF RFID tag antenna using non-uniform meandered lines for retail garments in the textile industry is presented. Based on an earlier UHF RFID tag antenna using nonuniform meandered lines, the proposed tag is fully bendable and aimed to be embedded in retail garments for long-life cycles. As a result, a relatively low cost, wide band, compactness and good conjugate matching with good dipole-like read range is presented. Results showed an antenna with a wide bandwidth of 900MHz and a long read range of 10.1m making the UHF RFID tag antenna using non-uniform meandered lines a potential candidate for retail garments in bendable applications of the textile industry. Simulations are corroborated by measurements and are in fairly agreement.

The out-of-plane displacement (OPD) of a circular dielectric elastomer actuator (DEA) membrane has been explored in recent years for a variety of important applications. Circular DEAs consist of an elastomer membrane that is prestretched to a rigid frame and coated with compliant electrodes. Such a simple configuration has found many interesting applications such as in, pumps, pulse tracking, hopping search and rescue robots, dielectric elastomer (DE) generators for renewable energy harvesting, linear actuators, and many others. Here, we present an easy-to-follow implementation of the OPD equations for circular DEAs via a detailed numerical solution using the shooting method (SM) on a system of differential algebraic equations (DAE), based on previous theoretical work. The SM numerical solution to the system of DAEs is applied to a practical range of values based on the reported literature. Analysis of the results and comparison against other studies are provided. The current work provides a go-to framework for implementation in further research and development.

Stir bar sorptive extraction (SBSE) was compared with standardized pump sampling regarding the prospects to assess airborne levels of polycyclic aromatic hydrocarbons (PAHs) in indoor environments. A historic railway water tower, which will be preserved aa technical monument for museum purposes, was sampled with both approaches because built-in insulation material was suspected to release PAHs to the indoor air. The 16 PAH on the US EPA list were quantified using gas chromatography with mass selection detection in filters from pump sampling after solvent extraction and on SBSE devices after thermal desorption. SBSE was seen to sample detectable PAH masses with excellent repeatability and a congener pattern largely similar to that observed with pump sampling. Congener patterns were however significantly different from that in the PAH source because release from the insulation material is largely triggered by the respective congener vapor pressures. Absolute masses in the ng range sampled by SBSE corresponded to airborne concentrations in the ng L -1 range determined by pump sampling. Principle differences between SBSE and pump sampling as well as prospects of SBSE as cost-effective and versatile complement of pump sampling are discussed.