Applications In Various Environments Research Articles

Highly efficient and stable deep-blue room temperature phosphorescence via through-space conjugation

Efficient blue and deep-blue room temperature phosphorescence (RTP) is still a great challenge due to the difficulties in populating and stabilizing the excitons in relatively high-lying states. Inorganic boric acid, lacking conventional luminophores in its structure, is generally not considered as efficient material for RTP. In this work, we illustrated how to make deep-blue RTP materials with both high emission efficiency (phosphorescence quantum yield of 45%) and an ultralong lifetime (2.9 s) through a heat treatment strategy. Moreover, a through-space conjugation assisted energy transfer and rigidification mechanism was proposed for explaining the simultaneous promoting of emission lifetime and efficiency. In addition, the deep-blue RTP materials displayed excellent stability against restrict external environments (such as high concentration acid, alkali, oxidant, reductant and organic solvents). Benefiting from these high-performance RTP materials, multi-level information encryption under harsh conditions was demonstrated. The research results thus provide a universal principle and strategy for designing stable and efficient blue RTP materials, which also extend their applications in various environments.

Superhydrophobic PDMS-pCA@CNWF Composite with UV-Resistant and Self-Cleaning Properties for Oil/Water Separation.

Oil separation is crucial for avoiding environmental pollution originating from industrial wastewater and oil spillage; therefore, it is essential to develop techniques for oil separation. Herein, a new membrane with superhydrophilicity was synthesized by a facile, green, and low-cost method. First, cellulose non-woven fabric (CNWF) was modified by poly (catechin) (pCA), which has good antioxidant and antibacterial activities, to make it unaffected by ultraviolet light and to improve the stability of the structure. Then, hydrolyzed polydimethylsiloxane (PDMS) was coated on the pCA@CNWF surface via chemical bonding to make the composite hydrophobic. This durable superhydrophobic fabric can be used to separate various oil/water mixtures by gravity-driven forces with high separation efficiency (over 98.9%). Additionally, the PDMS-pCA@CNWF possesses the advantages of flexibility, high efficiency, and an outstanding self-cleaning performance, and demonstrates significant potential for applications in various environments, even under various harsh conditions, which make it very promising for the treatment of oil pollution in practical applications.

Contact Information-Based Indoor Pedestrian Localization Using Bluetooth Low Energy Beacons

Indoor localization technologies are actively investigated to realize location-based applications in various environments, and indoor localization methods based on whether the received signal strength indicator (RSSI) is less than a threshold have been proposed previously. Such a proximity/non-proximity binary value is used in digital contact tracing applications to reduce the coronavirus disease effects. We proposed two indoor pedestrian localization methods based on contact information using bluetooth low energy (BLE) beacons, namely multilateration and cooperative localization. This study attempts to demonstrate the effectiveness of the proposed methods using only contact information. Through simulation experiments, we found that the proposed methods can achieve comparable accuracy to existing methods when the attenuation model is accurate. The difference in average localization error was 0.1 m between the proposed method 1 and range-based method, and 0.2 m between the proposed method 2 and fingerprinting method. We confirmed that the proposed methods using only contact information are robust against environmental changes even when the attenuation model is inaccurate. We consider that these contributions have added a new perspective on the use of contact information in the field of indoor localization, which aims to realize power-saving and cost reduction.

Speaker Diarisation of Vibroacoustic Intelligence from Drone Mounted Laser Doppler Vibrometers

Laser Doppler Vibrometers (LDVs) are exceptionally well suited to non-contact vibration sensing applications in various environments. This work focuses on diarisation of conversations that might be recorded via a drone-mounted LDV by reducing the effect of external noise, extracting useful features from frames of audio and clustering them into homogenous segments based on speaker identity. The two-step noise reduction (TSNR) technique was introduced to these vibroacoustic data for the first time and tested against Gaussian bandpass filtering for noise reduction from sources such as laser speckle and additional broadband ‘white’ noise. Feature extraction was then performed using a time-delay neural network, with the grouping of frames to a particular speaker tested with various clustering methods. Each noise reduction and clustering technique combination were tested on a twospeaker conversation recorded via the LDV. In the case of no added noise, the most effective combination was found to be the TSNR/Agglomerative Hierarchical Clustering (AHC) combination with a diarisation error rate of 6.13%. In the case of additional broadband noise, the most effective combination was found to be TSNR followed by Gaussian bandpass filtering then clustering via AHC with a diarisation error rate of 11.9%. With this work, another aspect of the challenge of covertly obtaining and interpreting vibroacoustic intelligence in remote and hostile environments using LDVs has been addressed.

Joining of Electrodes to Ultra-Thin Metallic Layers on Ceramic Substrates in Cryogenic Sensors.

Microjoining technologies are crucial for producing reliable electrical connections in modern microelectronic and optoelectronic devices, as well as for the assembly of electronic circuits, sensors, and batteries. However, the production of miniature sensors presents particular difficulties, due to their non-standard designs, unique functionality and applications in various environments. One of the main challenges relates to the fact that common methods such as reflow soldering or wave soldering cannot be applied to making joints to the materials used for the sensing layers (oxides, polymers, graphene, metallic layers) or to the thin metallic layers that act as contact pads. This problem applies especially to sensors designed to work at cryogenic temperatures. In this paper, we demonstrate a new method for the dynamic soldering of outer leads in the form of metallic strips made from thin metallic layers on ceramic substrates. These leads can be used as contact pads in sensors working in a wide temperature range. The joints produced using our method show excellent electrical, thermal, and mechanical properties in the temperature range of 15–300 K.

A systematic literature review on mobility in terrestrial and underwater wireless sensor networks

SummaryWireless sensor network (WSN) is one of the most significant technologies that gets much attention from researchers due to its promising applications in various environments. Mobility in wireless sensor networks contributes significantly to improving the performance of terrestrial wireless sensor networks (TWSNs) and underwater wireless sensor networks (UWSNs). This research's primary goal is to highlight the roles of mobility and mobile element tasks in enhancing terrestrial and underwater wireless sensor networks. Our systematic literature review (SLR) analyzed studies published between the periods of 2003 and January 2020. Out of 1762 studies retrieved by searching six online digital libraries and other resources, only 107 of them were selected for primary studies based on selection criteria and relevant to three identified research questions. This was followed by data extraction from the primary studies for answering the three SLR questions. The study reveals that mobility plays an essential role in improving network performance in TWSNs and UWSNs, especially in the aspects of coverage, energy efficiency, throughput, and connectivity. The study also identifies the tasks of the mobile elements in TWSNs and UWSNs, including data collection, localization, and charging. Moreover, it demonstrates the parameters of the mobile elements that should be considered when building networks. Finally, this study concludes by highlighting some open research issues that can be considered for future research.

Process Intensification through Directly Coupled Autothermal Operation of Chemical Reactors

Summary Autothermal operation of a chemical reactor involves coupling exothermic and endothermic chemical reactions for the purpose of thermal management without resorting to external energy sinks or sources. Often this is accomplished through regenerative or recuperative heat exchange between spatially or temporally separated exothermic and endothermic reactions. However, it is also possible to directly couple these reactions simultaneously within the same reactor volume, eliminating the heat-transfer bottleneck that characterizes much of chemical manufacture. It is not widely recognized that directly coupled autothermal operation allows dramatic process intensification. This perspective defines autothermal operation and contrasts it with conventional heat transfer for thermal management of chemical processes. The intensification and cost savings that can be achieved are quantified, and the implications to modular chemical process intensification are presented. Guidelines are proposed for designing directly coupled autothermal processes. Diverse examples are presented. Several challenges to expanding the field are critically discussed.

Bionic torus as a self-adaptive soft grasper in robots

For the development of advanced robots, there is an increasing demand to design self-adaptive envelope graspers that can take objects of unknown shapes, sizes, and softness. Inspired by the predation strategy of sea anemones, we propose a soft actuator by filling liquid into a torus. When a pulling force is applied at the interior skin of the torus, its exterior skin will roll inward and suck the target. Similar to the predation behavior of sea anemones, the inward crimping of the skin is able to grip and hold objects with different shapes, weights, and materials. By adjusting the rolling direction and length of the torus skin, the object could be engulfed, swallowed, and released. The prototype of such a gripper is fabricated, which demonstrates the versatility of application in various environments. This work provides an alternative route for designing self-adaptive graspers.

A flower-inspired divergent light-trapping structure with quasi-spherical symmetry towards a high-performance flexible photodetector.

Molybdenum disulfide (MoS2) has received widespread attention in recent years due to its exciting properties. However, the practical applications of MoS2 in optoelectronic devices are impeded by the power supply problem, the lack of flexibility, and the low light absorption for planar nanosheets and nanosheet arrays. Inspired by the elaborate architecture of the flower Tagetes erecta L., in this work, a self-assembled divergent MoS2 nanoflower (MoS2_F) with quasi-spherical symmetry is successfully synthesized by a facile one-step hydrothermal method. It is of significance that coupled with asymmetric silver electrodes and packaged by polymethyl methacrylate (PMMA), a self-powered flexible photodetector (PD) based on MoS2_F is actualized and shows an excellent flexible photoresponse performance at zero bias voltage. The divergent structure with quasi-spherical symmetry enables the MoS2_F to achieve strong broadband and omnidirectional absorption (92.7%) and ensures that the MoS2_F maintains the same physical contact on a different bending degree. Intriguingly, excellent flexibility and stability have been achieved as MoS2_F PD retains 91.4% of the initial efficiency even when bent to 151° and retains 92.5% of the initial efficiency even after 1000 bending cycles. Therefore, by a low-cost process, this work demonstrates an innovative avenue to fabricate a self-powered flexible photodetector with excellent light absorption, broadband response, flexibility, and stability, which is of great practical significance for optoelectronic applications in various environments.

Survey on Energy Efficient Routing Issues in IOMT

IOT is going to offer large number of applications in various environments for improving the quality of our lives. Routing issues become more and more challenging for low-power and lossy radio-links, multi-hop mesh topologies, the battery supplied nodes and frequently changed network topologies. So that IOT routing protocols has some challenges like traffic Patterns, Energy efficiency, Scalability, Mobility Energy-aware metrics for routing protocol in IOT are node energy, throughput, latency, link quality. The multimedia transmission in IOT depends on a routing protocol to determine stable and resource efficient path, and to provide varying levels of QoS/QoE based on different requirements. The Quality- of-Service (QoS)/Quality-of- experience (QoE ) guarantee for multimedia in internet of things . The current research and development activities have been restricted to scalar sensor data based IOT systems and overlooked the challenges of provisioning multimedia devices over IOT.

Preparation of Citric Acid Fermentation Waste-Based Mulch Films with Hydrophobic Surface by Poly(styrene-co-acrylate) Coatings

To improve the surface hydrophobicity of citric acid fermentation waste (CAFW)/poly(vinyl alcohol) (PVA) mulch films for their application in various environments, poly(styrene-co-acrylate) (PSA) is used as the single or double sides coatings of CAFW/PVA mulch films. The structure and properties of the obtained CAFW-based mulch films with PSA coatings are investigated. Attenuated total reflection Fourier transform infrared spectroscopy reveals that hydrogen bondings are formed between O–H bonds of the CAFW-based mulch film and C═O bonds of PSA coatings, which accounts for good interface adhesion between PSA coatings and CAFW-based mulch films. In addition, after PSA coatings, the elongation at break of the obtained films is obviously increased, whereas the tensile strength remains nearly unchanged, meanwhile the thermal property of CAFW-based mulch film is slightly improved. Importantly, the water contact angle of CAFW-based mulch films increases dramatically from 37 to 97° and the surface hydrophobicity ...

Development of pulse shape algorithms for discrimination between gamma and X-ray radiation pulses.

Influence of x-ray pulse generated from gamma spectrometers should be eliminated in applications, which typically uses pulse shape techniques between gamma and x-ray pulses. In this study, we proposed and tested several algorithms aiming to eliminate this influence. The algorithms are based on curve fitting (CF), artificial neural network (ANN), system identification, peak shape, amplitude search with curve fitting and pulse tracking methods. Gamma pulses and X-ray pulses are detected by NaI(TI) scintillator detector and Silicon lithium Si(Li) detector, respectively. The developed algorithms are tested using 32,000 total instantaneous detector events of acquired gamma pulses and 65,536 total instantaneous detector events of x-ray source. An algorithm using the least square curve fitting method is applied for differentiation between gamma and x-ray pulses. ANN is employed as a classifier for identification of extracted spectrum and Bispectrum features of gamma and x-ray pulses. A comparison between identification results due to extracted spectrum and Bispectrum features is established. System identification algorithm is then built to determine the detection system response of each radiation pulse, which includes various models to attain best fitting. These models are Auto-regressive model with external input (ARX), the linear parametric model (IV) and process models (P1D). The peak shape algorithm is also tried, which depends on the individual classification of pulse width. The amplitude search with curve fitting algorithm is implemented. Moreover, the pulse tracking algorithm is investigated for PSD between gamma and x-ray pulses. The maximum peak of contaminated pulse is tracked using a suggested peak search method. Then, pulse position is estimated using matrix method. Comparison between these algorithms is conducted based on the evaluation of light of residuals, fitting error and processing time. The results confirm that peak shape algorithm is the best one from computational speed point of view, while ANN algorithm using Bispectrum feature extraction method is the most appropriate one that yields 100% accuracy over noisy environment with longer processing time. In addition, the system identification algorithm is the optimal algorithm that achieves zero fitting error under clean environment. These proposed algorithms for PSD between gamma and x-ray pulses lead to design efficient spectrometers with optimal applicability in various environments.

A cross-layer learning automata based gateway selection method in multi-radio multi-channel wireless mesh networks

Wireless networks’ applications are increasing gradually necessitating their performance to enhance. Evolution of these networks over time indicates the need for algorithms which can operate based on their dynamic nature. Wireless mesh networks provide Intranet and Internet access for different applications in various environments. It is expected that the traffic load will be high on these networks. As gateway nodes are responsible for the traffic load transmission, gateway selection is known as one of the important research issues in that it can lead to optimized use of the network capacity and reduce congestion effects. In addition, utilizing multi-radio multi-channel architecture is one of the promising methods for increasing performance and decreasing interference. Channel assignment determines the most appropriate channel-radio associations for transmitting and receiving data through different channels simultaneously. Taking into account this architecture, this paper was written to propose a distributed gateway selection algorithm along with a cross-layer concept which predicts environment dynamics by learning automata. Experimental results demonstrate that the proposed method in various configurations on average improves packet delivery ratio 17.66%, throughput 5.36%, network overhead ratio 6.34%, and average end-to-end delay 15.94% higher than reinforcement learning-based best path routing algorithm (RLBPR), the best studied algorithm; therefore, it leads to more efficient utilization of network capacity compared to nearest gateway, minimum load index, expected transmission count, best path to best gateway, and RLBPR algorithms.

Ultra-thin and strong formvar-based membranes with controlled porosity for micro- and nano-scale systems

We present a methodology for developing ultra-thin and strong formvar-based membranes with controlled morphologies. Formvar is a thin hydrophilic and oleophilic polymer inert to most chemicals and resistant to radiation. The formvar-based membranes are viable materials as support structures in micro- and macro-scale systems depending on thinness and porosity control. Tunable sub-micron thick porous membranes with 20%–65% porosity were synthesized by controlling the ratios of formvar, glycerol, and chloroform. This synthesis process does not require complex separation or handling methods and allows for the production of strong, thin, and porous formvar-based membranes. An expansive array of these membrane characterizations including chemical compatibility, mechanical responses, wettability, as well as the mathematical simulations as a function of porosity has been presented. The wide range of chemical compatibility allows for membrane applications in various environments, where other polymers would not be suitable. Our formvar-based membranes were found to have an elastic modulus of 7.8 GPa, a surface free energy of 50 mN m−1 and an average thickness of 125 nm. Stochastic model simulations indicate that formvar with the porosity of ∼50% is the optimal membrane formulation, allowing the most material transfer across the membrane while also withstanding the highest simulated pressure loadings before tearing. Development of novel, resilient and versatile membranes with controlled porosity offers a wide range of exciting applications in the fields of nanoscience, microfluidics, and MEMS.

Self-Powered Si/CdS Flexible Photodetector with Broadband Response from 325 to 1550 nm Based on Pyro-phototronic Effect: An Approach for Photosensing below Bandgap Energy.

Cadmium sulfide (CdS) has received widespread attention as the building block of optoelectronic devices due to its extraordinary optoelectronic properties, low work function, and excellent thermal and chemical stability. Here, a self-powered flexible photodetector (PD) based on p-Si/n-CdS nanowires heterostructure is fabricated. By introducing the pyro-phototronic effect derived from wurtzite structured CdS, the self-powered PD shows a broadband response range, even beyond the bandgap limitation, from UV (325 nm) to near infrared (1550 nm) under zero bias with fast response speed. The light-induced pyroelectric potential is utilized to modulate the optoelectronic processes and thus improve the photoresponse performance. Lasers with different wavelengths have different effects on the self-powered PDs and corresponding working mechanisms are carefully investigated. Upon 325 nm laser illumination, the rise time and fall time of the self-powered PD are 245 and 277 µs, respectively, which are faster than those of most previously reported CdS-based nanostructure PDs. Meanwhile, the photoresponsivity R and specific detectivity D* regarding to the relative peak-to-peak current are both enhanced by 67.8 times, compared with those only based on the photovoltaic effect-induced photocurrent. The self-powered flexible PD with fast speed, stable, and broadband response is expected to have extensive applications in various environments.

The PRE-hospital Stroke Treatment Organization.

Background The PRE-hospital Stroke Treatment Organization was formed in 2016 as an international consortium of medical practitioners involved in pre-hospital treatment of patients with acute stroke. Aims PRE-hospital Stroke Treatment Organization's mission is to improve stroke outcomes by supporting research and advocacy for pre-hospital stroke treatment in Mobile Stroke Units. PRE-hospital Stroke Treatment Organization will provide a platform to enhance collaborative research across the spectrum of acute stroke management in the pre-hospital setting. PRE-hospital Stroke Treatment Organization will also facilitate the appropriate proliferation and distribution of Mobile Stroke Units by providing a forum for professional communication, resource for public education, and stimulus for government, industry, and philanthropic support. Summary of review In this "white paper", we describe the evidence supporting pre-hospital stroke treatment, progress to date, practical issues such as application in various environments and staffing, planned research initiatives, and organizational structure. Conclusions PRE-hospital Stroke Treatment Organization is not-for-profit, with membership open to anyone involved (or hoping to become involved) in pre-hospital stroke care. PRE-hospital Stroke Treatment Organization has a Steering Committee comprised of members from Europe, U.S., Canada, Australia, and other regions having a Mobile Stroke Unit in operation. PRE-hospital Stroke Treatment Organization convenes satellite meetings for membership at the International Stroke Conference and European Stroke Congress each year to address the PRE-hospital Stroke Treatment Organization mission. The first research collaborations agreed upon are to: (1) develop a list of common data elements to be collected by all Mobile Stroke Unit programs and entered into a common research database, and (2) develop a protocol for investigating the natural history of hyper-acute Intracerebral Hemorrhage.

Raman lasing and Fano lineshapes in a packaged fiber-coupled whispering-gallery-mode microresonator

We report Raman lasing and the optical analog of electromagnetically-induced-transparency (EIT) in a whispering-gallery-mode (WGM) microtoroid resonator embedded in a low refractive index polymer matrix together with a tapered fiber coupler. The microtoroid resonator supports both single mode and multimode Raman lasing with low power thresholds. Observations of Fano and EIT-like phenomena in a packaged microresonator will enable high resolution sensors and can be used in networks where slow-light effect is needed. These results will open up new possibilities for portable, robust, and stable WGM microlasers and resonator-based sensors for applications in various environments.

Investigation of Causes for Limiting the Load-Carrying Capacity of Meshing Elements of Spiroid Gears

Появившиеся относительно недавно спироидные передачи находят эффективное применение при различных условиях и режимах работы. Кроме того, существуют различия в применяемых материалах и технологиях изготовления зацепляющихся звеньев спироидных передач. Спироидные колеса можно изготавливать из полиамидов, спекаемых металлических порошков, бронзы, стали и чугуна. Червяк традиционно изготавливают из сталей с использованием термической или химико-термической обработки для повышения прочности и износостойкости. Технологические различия в свою очередь приводят к разным причинам снижениям прочности зубьев спироидных колес и витков червяка. В статье рассмотрены некоторые причины ограничения нагрузочной способности зацепляющихся звеньев спироидных передач. Проводимые многолетние испытания спироидных передач выявили различные виды разрушений для зубьев спироидных колес. Основной причиной разрушений пластмассовых спироидных колес является срез. Для порошковых колес характерны либо срез, либо излом. Однако витки спироидного червяка также могут ломаться неожиданно. Для определения отклонений в структуре и свойствах поверхностного слоя и сердцевины нитроцементованных червяков были проведены металлографические исследования. Из витков спироидных червяков были сделаны образцы, которые затем подвергались всем необходимым манипуляциям для получения микрошлифов.

Key Generation From Wireless Channels: A Review

Key generation from the randomness of wireless channels is a promising alternative to public key cryptography for the establishment of cryptographic keys between any two users. This paper reviews the current techniques for wireless key generation. The principles, performance metrics and key generation procedure are comprehensively surveyed. Methods for optimizing the performance of key generation are also discussed. Key generation applications in various environments are then introduced along with the challenges of applying the approach in each scenario. The paper concludes with some suggestions for future studies.

Solvent effects on the thermal isomerization of a rotary molecular motor.

As molecular machines move to exciting applications in various environments, the study of medium effects becomes increasingly relevant. It is difficult to predict how, for example, the large apolar structure of a light-driven rotary molecular motor is affected by a biological setting or surface proximity, while for future nanotechnology precise fine tuning and full understanding of the isomerization process are of the utmost importance. Previous investigations into solvent effects have mainly focused on the relatively large solvent-solute interaction of hydrogen bonding or polarization induced by the isomerization process. We present a detailed study of a key step in the rotary process i.e. the thermal helix inversion of a completely apolar rotary molecular motor in 50 different solvents and solvent mixtures. Due to the relative inertness of this probe, we are able to study the influence of subtle solvent-solvent interactions upon the rate of rotation. Statistical analysis reveals which solvent parameters govern the isomerization process.