High Recovery Speed Research Articles

High recovery speed optical humidity sensing enabled with GQD for non-contact finger distance detection

Finger distance perception plays a crucial role in enabling humanoid intelligent robotic systems to achieve smooth interaction with humans. Here, a rapidly response optical humidity sensor enabled with graphene quantum dots (GQD) for non-contact finger distance detection was proposed. The GQD was prepared through the functionalization of graphene oxide (GO) with hydrophilic groups. This modification enhances the responsiveness of GO to atmospheric humidity and promotes the deposition of conformal films of functional materials on the surfaces of optical fiber. Utilizing a light-driven coating method, the GQD was deposited onto a tilted fiber Bragg grating (TFBG) to fabricate humidity sensor. When water molecules were absorbed by GQD, the dielectric constant of GQD film was changed, causing an alteration in the intensities of the TFBG’s cladding modes. The proposed sensor shows a sensitivity of 0.032 dB/%RH with the equilibrium response and recovery time of 3.66 s and 0.92 s, respectively. The equilibrium recovery time is the fastest as far as we know. Furthermore, the sensor is capable of precisely identifying the action of a finger, such as approaching, remaining, and departing with a detection range of 0–10 mm.

Single Failure Recovery Method for Erasure Coded Storage System with Heterogeneous Devices

As the demand of data reliability becomes more and more larger, most of today's storage systems adopt erasure codes to assure the data could be reconstructed when suffering from physical device failures. In order to fast recover the lost data from a single failure, recovery optimization methods have attracted a lot of attention in recent years. However, most of the existing optimization methods focus on homogeneous devices, ignoring the fact that the storage devices are usually heterogeneous. In this paper, we propose a new recovery optimization method named HSR (Heterogeneous Storage Recovery) method, which uses both loads and speed rate among physical devices as the optimization target, in order to further improve the recovery performance for heterogeneous devices. The experiment results show that, compared to existing popular recovery optimization methods, HSR method gains much higher recovery speed over heterogeneous storage devices.

Stretchable Strain Sensors Fabricated by Screen Printing of Silver Paste on the Surface Modified Transparent Elastomeric Polyurethane Films

Strain sensors for human-motion detection must offer high stretchability, high sensitivity, fast response, and high recovery speed. In this study, we choose silver paste as a sensing material and use a screen printing method to fabricate the strain sensor based upon an electrical-resistance mechanism. After curing elastomeric polyurethane film with a thickness of 150 μm on PET film, the polyester resin mixed with blocked isocyanate curing agent was coated as a masking layer to reduce the film’s stickiness. The effect of the polyester masking layer upon the silver paste screen printing process was examined using a rolling-ball-tack test, TGA analysis of polyester resins, and cured silver-electrode films. The cost-effective strain sensor fabricated by using silver paste and screen printing processes on the stretchable-polyurethane-substrate film showed high sensitivity and fast response in a strain range of up to 100%.

Reconsidering Single Disk Failure Recovery for Erasure Coded Storage Systems: Optimizing Load Balancing in Stack-Level

The fast growing of data scale encourages the wide employment of data disks with large storage capacity. However, a mass of data disks' equipment will in turn increase the probability of data loss or damage, because of the appearance of various kinds of disk failures. To ensure the intactness of the hosted data, modern storage systems usually adopt erasure codes, which can recover the lost data by pre-storing a small amount of redundant information. As the most common case among all the recovery mechanisms, the single disk failure recovery has been receiving intensive attentions for the past few years. However, most of existing works still take the stripe-level recovery as their only consideration, and a considerable performance improvement on single failure disk reconstruction in the stack-level (i.e., a group of rotated stripes) is missed. To seize this potential improvement, in this paper we systematically study the problem of single failure recovery in the stack-level. We first propose two recovery mechanism based on greedy algorithm to seek for the near-optimal solution (BP-Scheme and STP-Scheme) for any erasure array code in stack level, and further design a rotated recovery algorithm (RR-Algorithm) to eliminate the size of required memory. Through a rigorous statistic analysis and intensive evaluation on a real system, the results show that BP-Scheme gains 3.4 to 38.9 percent (the average is 21.2 percent) higher recovery speed than Khan's Scheme and 3.4 to 34.8 percent (the average is 19.1 percent) higher recovery speed than Luo's U-Scheme, while STP-Scheme owns 3.4 to 46.9 percent (the average is 25.15 percent) and 3.4 to 41.1 percent (the average is 22.3 percent) higher recovery speed than Khan's Scheme and Luo's U-Scheme, respectively.

Review of inorganic semiconductor based ultraviolet photodetectors with high internal gain and fast recovery speed

Ultraviolet (UV) photodetectors have important applications in military field, industrial field, environmental field, etc. High performance UV photodetectors characterised as high internal gain (G) and high recovery speed has been studied in decades. In this article, we provide a comprehensive review about recent works on increasing the internal gain of UV photodetectors by improving device configuration, optimising the diameter of the nanowire, applying surface functionalisation and Schottky contact. And the possible solutions to the persistent photoconductivity (PPC) problem which prolongs the recovery time are also discussed.

Effects of solvents on the band energetics of nanostructured BaTiO<SUB align="right">3 electrodes for dye sensitised solar cells

Ultraviolet (UV) photodetectors have important applications in military field, industrial field, environmental field, etc. High performance UV photodetectors characterised as high internal gain (G) and high recovery speed has been studied in decades. In this article, we provide a comprehensive review about recent works on increasing the internal gain of UV photodetectors by improving device configuration, optimising the diameter of the nanowire, applying surface functionalisation and Schottky contact. And the possible solutions to the persistent photoconductivity (PPC) problem which prolongs the recovery time are also discussed.

Graphene Oxide Enabled Polymeric Shape Memory Composites for Enhanced Electro-Actuation

An effective approach to improve the electrical properties and electro-activated performance of shape memory polymer (SMP) nanocomposites has been demonstrated via a synergistic effect from carbon fibre and self-assembled graphene oxide (GO). The surface modified GO has been grafted onto carbon fibre to enhance the interfacial strength with SMP matrix through van-der-Waals bonds and covalent crosslinking. Carbon fibre enhances the performance of electrical actuation of SMP through Joule heating. Furthermore, the temperature distribution within the SMP nanocomposite during Joule heating becomes uniform, resulting in a significant enhancement of shape recovery and electro-actuation performance of high recovery speed.

The resilience of regional labour markets to economic shocks: Exploring the role of interactions among firms and workers

To date, theoretical and empirical insights in the determinants of regional resilience are still limited. Using a model, we explore how three regional factors jointly contribute to the resilience of regional labour markets to economic shocks. The localization of the supply network (1) is used to model the propagation of the shock, while possibilities for intersectoral (2) and interregional labour mobility (3) to analyse the recovery. An application of the model to Dutch data suggests that labour markets in centrally located and service-oriented regions have, on average, a higher recovery speed, irrespective of the type of shock hitting the economy.

Synthesis and Characterization of Novel Liquid Crystalline Epoxides with Lateral Substituent Showing Imposing Shape Memory Properties

In this work, a series of novel shape memory liquid crystalline (LC) epoxides with lateral substituent were prepared and characterized. Dynamic mechanical analysis (DMA) and shape memory testing were used to investigate on the thermo-mechanical properties and shape memory effects of prepared samples. The results showed that the modulus in the rubbery region (ER ) decreased as the length of lateral alkyl group increases. And more than 95% of the deformation can be fixed as the sample was cooled down below the glass transition temperature (Tg), which was determined by differential scanning calorimetry (DSC) measurement, and can be recovered completely as heating. Effects of the curing agent and substituent on the shape memory behavior were also studied. We found that LC epoxides cured by aromatic diamine have a higher recovery speed. The recovering speeds of the shape memory decreased as the length of lateral alkyl group inscreased. The local ordered structures and the lateral substituent played an important role in shape memory effects.

Shape Memory Behaviour of Functionalised Poly(ε-caprolactone) Crosslinked by Hexamethylene-Diisocyanate

In this study, the shape memory behaviour of poly(ε-caprolactone) (PCL) with different crosslinking degrees was investigated. PCL was first functionalised with maleic anhydride (MA) and glycidyl methacrylate (GMA), and successively chemically crosslinked by hexamethylene diisocianate (HMDI). The crosslinking reaction was studied through with a rotational stress rheometer, while the shape memory behaviour was analyzed with cyclic thermomechanical experiments and optical microscopy. The results show that the new materials exhibit good shape memory behaviour and good stability of the shape recovery under consecutive cycles in the range 55 - 70°C, can reach high level of stretching, and are furthermore characterised by high recovery speed. These results are promising for potential practical applications, as biomaterials for embolic devices in minimally invasive surgery. Keywords: Shape memory effect, poly(ε-caprolactone), crosslinking

Room-temperature high-sensitivity detection of ammonia gas using the capacitance of carbon/silicon heterojunctions

Ammonia (NH3) sensors based on carbon/silicon (C/Si) heterojunctions are demonstrated at room temperature (RT). Upon exposure to NH3 molecules (0.2 ml l−1) at RT, the interface capacitance of C/Si junction increases dramatically, to about 230%. The results show that C/Si junctions have high NH3 gas sensitivity, rapid response and high recovery speed at RT. This phenomenon can be attributed to the change of the potential barrier width of the junction, which is caused by the adsorption of NH3 gas molecules. The C/Si junctions can greatly amplify the detection sensitivity of the nano-sized carbon so that the C/Si junctions act as excellent RT gas sensors.

Ethanol gas sensitivity of carbon nanotip arrays/n-Si heterojunctions at room temperature

Carbon nanotip arrays were grown from silicon substrates via direct current magnetron sputtering at room temperature (RT). The simple carbon nanotip arrays/n-Si (C∕Si) heterojunctions were used to detect ethanol gas at RT. The results show that the C∕Si junctions have high ethanol gas sensitivity, rapid response, and high recovery speed at RT. Upon exposure to ethanol gas (0.64g∕l) at RT, the resistance of the junction decreases by 35% at a given positive voltage of 8V. Moreover, the interface capacitance of the junction at 5kHz can increase by about 40% rapidly when exposed to ethanol gas. The phenomena should be attributed to the change in the Fermi level of the carbon film caused by adsorbing electrons from ethanol molecules. The study shows that the C∕Si junctions have potential application as ethanol gas sensors.

A virtual disk environment for providing file system recovery

File system recovery (FSR) is a kind of recovery facility that allows users to roll back the file system state to a previous state. In this paper, we present a virtual disk environment (VDE) which allows previous write operations to a hard disk to be undone, and previous version of files to be recovered. It can be used to recover the file system quickly even when computer system suffers the serious disaster such as system crash or boot failure. The VDE is same as virtual disk in the virtual machine (VM) environment in some way, but it can be applied to the environment without VM supports. Algorithms for implementing the VDE are presented and its implementation on Windows platform is discussed. Based on the implementation, the experimental results of the VDE performance are analyzed. Comparing with other FSRs, the main advantage of the VDE is low overhead and high recovery speed.

Behaviour of lubricant migration in particulate magnetic recording media

The effect of the recovery speed of lubricant on the durability of particulate magnetic media is presented in this paper. The use of newly synthesized perfluoropolyethers (PEPEs) in particulate media allows us to evaluate the amount of surface lubricant and the migration by X-ray photoelectron spectroscopy (XPS). The migration rate of the lubricant is evaluated as the change of the XPS peak area after argon etching to remove the surface lubricant. A recovery speed depends on the kind of lubricant and way of coating. Furthermore, lubricant of higher recovery speed has better stability of friction coefficient.

Stacked rotating bipolar electrode cell for recovery of copper from dilute cupric sulfate solution

A novel bipolar electrode cell, which we refer to as a stacked rotating bipolar electrode cell, has been developed for recovery of heavy metals from dilute solutions. The cell consists of two feeder electrodes and four stator bipolar electrodes alternating with five rotor bipolar electrodes. Fins are mounted on the anode surfaces to promote turbulence and scrape of the deposited copper. The characteristics were studied in batch operation of powdery copper recovery from cupric sulfate solutions in the concentration range from 500 to 10 ppm Cu 2+. A high recovery speed is achieved due to the excellent stirring effect of the rotating electrodes and the increase in micro-turbulence at the large active surface caused by the deposition of powdery copper. The high speed electrolysis and the large surface area per until cell volume as attained by stacking the bipolar electrodes also lead to a high space time yield.