Of the different branches of indoor localization research, WiFi fingerprinting has drawn significant attention over the past decade. These localization systems function by comparing WiFi received ...signal strength indicator (RSSI) and a pre-established location-specific fingerprint map. However, due to the time-variant wireless signal strength, the RSSI fingerprint map needs to be calibrated periodically, incurring high labor and time costs. In addition, biased RSSI measurements across devices along with transmission power control techniques of WiFi routers further undermine the fidelity of existing fingerprint-based localization systems. To remedy these problems, we propose GradIent FingerprinTing (GIFT) which leverages a more stable RSSI gradient. GIFT first builds a gradient-based fingerprint map (Gmap) by comparing absolute RSSI values at nearby positions, and then runs an online extended particle filter (EPF) to localize the user/device. By incorporating Gmap, GIFT is more adaptive to the time-variant RSSI in indoor environments, thus effectively reducing the overhead of fingerprint map calibration. We implemented GIFT on Android smartphones and tablets, and conducted extensive experiments in a five-story campus building. GIFT is shown to achieve an 80 percentile accuracy of 5.6 m with dynamic WiFi signals.
Owing to the earth‐abundant resources, cost effective materials and stable electrochemical properties, sodium‐ions batteries (SIBs) show long‐term potential in responding to the rapid consumption of ...lithium resources and the ever‐increasing development of new energy storage devices. Nevertheless, the intrinsic properties of the large ion radius (Na+ 1.02 Å vs Li+ 0.76 Å) and positive reduction potential (Na/Na+ −2.71 V vs Li/Li+ −3.04 V) may impede ion diffusion, thus causing serious volume expansion, resulting in poor cycling stability. To address these issues, the incorporation of active sites into carbonaceous anode is considered as an efficient strategy to enhance interfacial compatibility, enlarge interlayer distance, and supply reversible Faradic pseudo‐capacitance. Herein, the multiple active sites carbonaceous anodes for SIBs anode are comprehensively reviewed. Typically, carbonaceous materials are categorized into diffusion and surface controlled based on Na storage mechanism, and the concepts of intrinsic/extrinsic active sites are proposed according to the types of active sites. Furthermore, to reveal the reaction kinetics and guide the rational design of high performance anodes, the (spectro) electrochemical analysis methods and corresponding key parameters are introduced. Additionally, primary superiorities, essential issues, and supposed solutions of multiple active sites carbonaceous Na anodes are discussed and the future development directions are also proposed. This review may provide new design thoughts for high performance carbonaceous Na storage anodes.
The multiple active sites in carbonaceous Na storage anodes are categorized into intrinsic and extrinsic according to their origin, and further subdivided based on their reaction mechanism. Moreover, various electrochemical analysis methods and corresponding key parameters are introduced to deepen reaction mechanism and guide the rational design.
With the depletion of oil and natural reserves, gasoline-bioethanol blend has been considered as one of the finest alternative fuels. However, the fuel blend can also lead to higher fuel consumption ...as a result of adverse influence. Hydrogen as fuel additive contains many benefits in comparison to other petroleum since it promotes oxidation and decreases pollutant compounds during the combustion process. Therefore, this study aims to investigate the effect of pollutant emissions, fuel consumption and well-to-wheel GHG emissions from a vehicle operating with gasoline-bioethanol blend (E3, E6 and E10), and hydrogen produced (0.6 LPM) on-board under cold start and FTP-75 transient cycle. The results show that hydrogen addition fueled with gasoline-bioethanol blend (E6 and E10) improves diffusion speed and homogeneous mixing, benefiting the complete combustion of fuel-air mixture. The significant reduction of CO, HC and NOx could be found under cold start and FTP-75. The reduction of 0.096, 1.19 and 1.10% on fuel consumption were obtained for E3, E6 and E10 with hydrogen addition. From the environmental point of view, the E10 with and without hydrogen addition appears to be agreeable since the outcome of well-to-wheel GHG emissions account for significant reduction in comparison with the base fuel (G0).
•The effect of cold start and full cycle by FTP-75 condition were studied.•Hydrogen addition with E6, E10 reduced accumulated emission mass in cold start.•Vehicle fuel consumption was reduced by hydrogen addition.•Well-to-tank accounts for 22.3% of the well-to-wheel greenhouse gas emissions.•Compared to conventional gasoline, greenhouse gas was found reduced by 6.95% in E10.
Eighteen carbonyl species in C_1-C_（10） were measured in the dining areas,kitchens and exhaust streams of six different restaurant types in Kaohsiung,southern Taiwan.Measured results in the dining ...areas show that Japanese barbecue（45.06 ppb） had the highest total carbonyl concentrations（sum of 18 compounds）,followed by Chinese hotpot（38.21 ppb）,Chinese stir-frying（8.99 ppb）,Western fast-food（8.22 ppb）,Chinese-Western mixed style（7.38 ppb）,and Chinese buffet（3.08 ppb）,due to their different arrangements for dining and cooking spaces and different cooking methods.On average,low carbon-containing species（C_1-C_4）,e.g.,formaldehyde,acetaldehyde,acetone and butyraldehyde were dominant and contributed 55.01%-94.52%of total carbonyls in the dining areas of all restaurants.Meanwhile,Chinese-Western mixed restaurants（45.48 ppb） had high total carbonyl concentrations in kitchens mainly because of its small kitchen and poor ventilation.However,high carbon-containing species（C_5-C_（10）） such as hexaldehyde,heptaldehyde and nonanaldehyde（16.62%-77.00%of total carbonyls） contributed comparatively with low carbon-containing compounds（23.01%-83.39%of total carbonyls） in kitchens.Furthermore,Chinese stir-frying（132.10 ppb）,Japanese barbecue（125.62 ppb）,Western fast-food（122.67 ppb）,and Chinese buffet（119.96 ppb） were the four restaurant types with the highest total carbonyl concentrations in exhaust streams,indicating that stir-frying and grilling are inclined to produce polluted gases.Health risk assessments indicate that Chinese hotpot and Japanese barbecue exceeded the limits of cancer risk（10~（-6）） and hazard index（=1）,mainly due to high concentrations of formaldehyde.The other four restaurants were below both limits.
Both interference alignment (IA) and interference neutralization (IN) are exploited for coordinated multi-point (CoMP) communications. With the cooperation of the base station (BS), a transmit ...precoder and a receive filter are jointly designed, and concurrent transmissions of multiple data streams are then enabled. In the design of a precoder, the IN is applied to the interferences carrying the same data so as to align the interfering signals in the opposite direction in a subspace. On the other hand, for interferences carrying different information, IA is employed to align them in the same direction in a subspace, thus reducing the interference signal observed at the receiver side. Based on different precoding schemes at the transmitter's side, receivers adopt zero forcing (ZF) so as to recover the desired data. The proposed IA- and IN-based CoMP (IAN-CoMP) mechanism can achieve effective interference cancellation and suppression by exploiting limited and flexible collaboration at the BS side. It can also make a flexible tradeoff between the cooperation overhead and the system's achievable degrees of freedom (DoFs). We extend the mechanism to general cases where the antenna configurations at both the transmitter and receiver sides, the number of transmitters participating in CoMP, and that of simultaneously served users are variable. Moreover, we discuss both single-location and multi-location-based realizations of the IAN-CoMP. Finally, by defining the average transmit and receive cooperation order, we analyze the upper bound for IAN-CoMP. Our in-depth simulation shows that the IAN-CoMP can significantly improve the spectral efficiency (SE) for cell-edge users.
Wireless charging is a promising way to solve the energy constraint problem in sensor networks. While extensive efforts have been made to improve the performance of charging and communication in ...wireless rechargeable sensor networks (WRSNs), little has been done to address the operation scheduling problem. To fill this void, we propose a joint energy replenishment and scheduling mechanism so as to maximize the network lifetime while making strict sensing guarantees in the WRSN. We first formulate the problem in a general 2-D space and prove its NP-completeness. We then devise an f-approximate scheduling mechanism by transforming the classical minimum set cover problem and develop an optimal energy-replenish strategy based on the energy consumption of nodes returned by the scheduling mechanism. Large-scale simulation results validate our design and show a 39.2% improvement of network lifetime over a baseline method.
The major obstacle to biodiesel commercialization is the high cost of biodiesel. Biodiesel made from waste cooking oil is an economical source that can effectively reduce raw material cost. Although ...using a microwave heating system to improve the yields of waste-cooking-oil biodiesel has received little attention in the literature, experimental results indicate that it outperforms conventional heating, with the best performances found with 0.75 wt% sodium hydroxide (NaOH) and 0.75 wt% sodium methoxide (CH3ONa) catalysts, respectively. The biodiesel yields produced with CH3ONa catalyst are higher than those produced with NaOH catalyst. An increase in the reaction time from 1 to 3 min significantly increases the yield, which decreases with a further increase to 6 min. A methanol-to-oil molar ratio of 6 is suitable for the synthesis of biodiesel. The biodiesel yields increase with increasing reaction power. However, the microwave output must not be too high as it may damage the organic molecules. The optimal reaction conditions are 0.75 wt% CH3ONa catalyst, a methanol-to-oil molar ratio of 6, a reaction time of 3 min, and a microwave power of 750 W.
► Biodiesel from waste cooking oil is an effective strategy for reducing cost and solving the problem of waste oil. ► Microwave system can increase reaction rate, product yields, and purity of products. ► Sodium methoxide would be used as catalysts to increases reaction rate of biodiesel.
The effect of ambient PM
10
and PM
2.5
on lung function modified by body muscle and adipose tissue is not fully understood at present. Our aims were to investigate the association between seasonal ...average air pollutants and lung function in asthmatic patients modified by body composition indicators. In this cross-sectional study, we recruited 914 doctor-diagnosed asthmatic patients, and performed interaction and stratified analysis using the median values of total body muscle (TBM), total body fat (TBF), and percentage body fat (PBF) as well as body mass index (BMI) =25 as the cutoff points of the high/low body composition groups. The adjusted
R
2
values of the developed LUR models of PM
2.5
and PM
10
were 91.4% and 90.5% and also verified by cross-validation, respectively. After adjusting for confounding factors, we found that TBM significantly modified the association between PM
10
and lung function among asthma patients (interaction
P
value <0.05). In the low TBM group, seasonal average concentrations of PM
10
estimated by the LUR model increased by 10 μg/m
3
, and negative associations with lung function indicators were observed. For obese patients with BMI>25 and high TBF, the increase in PM
10
was associated with the decrease in lung function. The asthma patients with obesity and low total body muscle were more susceptible to adverse effects of PM
10
on lung function.
•The hydrogen supplement enhances diesel engine thermal efficiency.•The hydrogen produced from water electrolysis can reduce the fuel consumption.•H2 addition reduces the traditional pollutants at ...idling condition.•A great improvement on CO, CO2 emissions was observed with hydrogen addition.•An important reduction on NOx was achieved with H2 addition at low loads.
This study aimed to investigate the effect of conventional diesel engine through the addition of H2 mixture, generated through water electrolysis. In this work, three different ratios of diesel–hydrogen blends, 0%, 0.6% and 1.2% hydrogen by volume used, respectively. The experiments were carried out at the idling condition under constant speed from the low to high engine load with the different amount of H2 mixture. The results showed that the brake thermal efficiency (BTE) increased as the brake specific fuel consumption (BSFC) decreased with an increasing amount of hydrogen. The hydrogen addition leads to reduce the emissions of carbon dioxide (CO2) and carbon monoxide (CO). At the high operation load, the reduction in emissions was the most significant, but the total hydrocarbon (THC) emissions increased 4.94% and 13.1% on average with the low level of hydrogen addition (0.6% and 1.2% by volume). Nevertheless, the addition of hydrogen lowered nitrogen oxide (NOx) emissions at the idling and low load conditions, but increased at the high load, since the thermal NOx dominated at the higher temperature. Consequently, the addition of low level hydrogen decreased CO and CO2 emissions, whereas the THC and NOx emissions increased at the high engine load.
Chlorine-containing organic compounds were discharged informally as a result of untreated industrial wastewater, which caused groundwater pollution. In this study, titanium dioxide nanotube arrays ...(TNAs) were modified with copper oxide to photoelectrochemical (PEC) active persulfate to degrade trichloroethylene (TCE). The SEM results show copper nano-particles with a cubic shape were successfully deposited on the surface of TNAs. The results of UV–vis analysis indicate the absorption wavelengths red-shift to 550–600 nm for better light utilization. CuO/TNAs were dominated by the anatase phase after sintering at 450 °C with significant visible light response. The chemical contents for the surface of CuO/TNAs are 23.7, 53.4, 18.4 and 4.4% for C, O, Ti and Cu, respectively. The photocurrent of CuO/TNAs is 1.89 times higher than that of TNAs-93 cm^2–1hr under 100 W Hg-lamp illuminations. This demonstrates the efficiency of light utilization of TNAs was improved by the modification with copper nanoparticles. The degradation rate of TCE in the anodic chamber is more effective than that in the cathodic chamber because of the synergistic effect of hydroxyl and sulfate radicals. The mechanism of TCE degradation via persulfate in the PEC system was proposed and discussed in detail.
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•CuO/TNAs was synthesized successfully via square wave voltammetry electrochemical deposition method.•Recombination of photo-generated holes and electrons were greatly reduced.•TCE degradation was enhanced by synergetic effect of OH⋅ and SO4−.•Mechanism of TCE degradation via persulfate in PEC system was proposed.
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