The high repair cost of (n, k) Maximum Distance Separable (MDS) erasure codes has recently motivated a new class of MDS codes, called Repair MDS codes, that can significantly reduce repair bandwidth ...over conventional MDS codes. In this paper, we describe (n, k, d) Exact-Repair MDS codes, which allow for any failed node to be repaired exactly with access to d survivor nodes, where k ≤ d ≤ n-1. We construct Exact-Repair MDS codes that are optimal in repair bandwidth for the cases of: (α) k/n ≤ 1/2 and d ≥ 2k - 1 1 ; (b) k ≤ 3. Our codes are deterministic and require a finite-field size of at most 2(n - k). Our constructive codes are based on interference alignment techniques.
We first demonstrate delta-sigma digitization and coherent transmission of data over cable system interface specification (DOCSIS) 3.1 signals in a hybrid fiber coax (HFC) network. Twenty 192-MHz ...DOCSIS 3.1 channels with modulation up to 16384QAM are digitized by a low-pass cascade resonator feedback (CRFB) delta-sigma analog-to-digital converter (ADC) and transmitted over 80-km fiber using coherent single-λ 128-Gb/s dual-polarization (DP) quadrature phase-shift keying (QPSK) and 256-Gb/s DP-16QAM optical links. Both one-bit and two-bit delta-sigma digitization are implemented and supported by the QPSK and 16QAM coherent transmission systems, respectively. To facilitate its practical application in access networks, the coherent system is built using a low-cost narrow-band optical modulator and RF amplifiers. Modulation error ratio (MER) larger than 50 dB is successfully demonstrated for all 20 DOCSIS 3.1 channels, and high-order modulation up to 16384QAM is delivered over fiber for the first time in HFC networks. The raw DOCSIS data capacity is 54 Gb/s with net user information ∼45 Gb/s. Moreover, the bit error ratio (BER) tolerance is evaluated by measuring the MER performance as BER increases. Negligible MER degradation is observed for BER up to 1.5 × 10 −6 and 1.7 × 10 −4 for one-bit and two-bit digitization, respectively.
Summary
Mycelial growth attracts academic and commercial interest because of its ability to upcycle agricultural and industrial wastes into economical and environmentally sustainable composite ...materials using a natural, low‐energy manufacturing process able to sequester carbon. This study aims to characterise the effect of varying ratios of high silica agricultural and industrial wastes on the flammability of mycelium composites, relative to typical synthetic construction materials. The results reveal that mycelium composites are safer than the traditional construction materials considered, producing much lower average and peak heat release rates and longer time to flashover. They also release significantly less smoke and CO2, although CO production fluctuated. Rice hulls yielded significant char and silica ash which improved fire performance, but composites containing glass fines exhibited the best fire performance because of their significantly higher silica concentrations and low combustible material content. Higher concentrations of glass fines increased volume‐specific cost but reduced mass‐specific and density‐specific costs. The findings of this study show that mycelium composites are a very economical alternative to highly flammable petroleum‐derived and natural gas‐derived synthetic polymers and engineered woods for applications including insulation, furniture, and panelling.
Posterior distributions on parameters computed from experimental data using Bayesian techniques are only as accurate as the models used to construct them. In many applications, these models are ...incomplete, which both reduces the prospects of detection and leads to a systematic error in the parameter estimates. In the analysis of data from gravitational wave detectors, for example, accurate waveform templates can be computed using numerical methods, but the prohibitive cost of these simulations means this can only be done for a small handful of parameters. In this Letter, a novel method to fold model uncertainties into data analysis is proposed; the waveform uncertainty is analytically marginalized over using with a prior distribution constructed by using Gaussian process regression to interpolate the waveform difference from a small training set of accurate templates. The method is well motivated, easy to implement, and no more computationally expensive than standard techniques. The new method is shown to perform extremely well when applied to a toy problem. While we use the application to gravitational wave data analysis to motivate and illustrate the technique, it can be applied in any context where model uncertainties exist.
1. Many studies testing the evolution of increased competitive ability hypothesis have focused on whether plants from invasive populations of a species show reduced allocation to defence and ...increased allocation to growth than plants from native populations. But few have attempted to understand ecophysiological mechanisms by which decreased allocation to defence may increase growth. 2. Previously, we found that invasive Ageratina adenophora plants increase nitrogen allocation to photosynthesis and reduce allocation to cell walls compared with native Ageratina plants, suggesting a shift from defence to growth in invasive populations. Here, carrying this work forward, we measured construction costs and benefits associated with photosynthesis at light saturation to leaves. We hypothesized that invasive Ageratina populations might employ a quicker return energy‐use strategy by increasing light‐saturated photosynthetic rates and photosynthetic energy‐use efficiency (PEUE) and by decreasing leaf construction costs. 3. Faster‐growing plants from invasive populations (China and India) had significantly higher leaf nitrogen concentrations and specific leaf areas than plants from native populations (Mexico). Inconsistent with our prediction, leaf construction costs were not significantly different between plants from invasive and native populations, but higher light‐saturated photosynthetic rates and in turn higher PEUE resulted in a significantly shorter payback time of construction costs, which allowed plants from invasive populations to grow faster. 4. Synthesis. Our results indicate that Ageratina plants from populations in non‐native ranges have a distinct quick return energy‐use strategy, a high PEUE and a short payback time but not lower construction costs, which might provide a mechanistic explanation for the commonly observed increase in growth when plants are introduced to new parts of the world. To our knowledge, this is the first study to compare energy‐use strategy for plants from invasive and native populations of a noxious invasive species. We cannot exclude some alternative hypotheses for these patterns, such as founder effects, but these ecophysiological differences might provide mechanistic insight for how the evolution of decreased allocation to defence may increase growth and competitive ability.
Exploratory innovation is a pivotal way to seize future opportunities in green manufacturing innovation ecosystems, and exploitative innovation is conducive to expanding existing markets and ...resources, so it is essential to discuss the balanced incentive strategy of dual innovation for the sustainable development of ecosystems. Based on the hierarchical structure, this paper divides the core subjects in the green manufacturing innovation ecosystem into the application layer, the support layer, and the scientific research layer, constructs the differential game model of the no-incentive scenario, the cost-sharing scenario, and the collaborative scenario, and discusses the incentive strategies of the three types of subjects and the ecosystem in the evolution process of the dual innovation balance. The conclusions are as follows: (1) The level of dual innovation balance effort of the three types of subjects decreases with the increase of resource costs and environmental construction costs and increases with the increase of innovation balance capacity; (2) Cost sharing from the application layer to the support layer and the scientific research layer can enhance the effort level of both, which in turn enhances the optimal benefits for the three types of subjects and the ecosystem as a whole; (3) In the collaborative scenario, the level of effort and total ecosystem benefits of the innovation balance of the three types of subjects are strictly better than in the no incentive scenario, and the Pareto-optimality of the three subjects and the ecosystem will be realized after the coefficients of the distribution of benefits among the three types of subjects are determined. Based on this, this paper puts forward specific suggestions for the optimization of the structural relationship of the innovation body hierarchy, the exploitation of green manufacturing resources, and the macro-planning of the management department.
This paper presents an innovative water photovoltaic thermal collector prototype. One of the main novelties of such system is its economic affordability, obtained through low-cost materials. The ...collector, constructed and experimentally tested at the University of Patras (Greece), is composed of a polycrystalline photovoltaic module coupled to eleven plastic pipes for water heating, located under the PV panel in an aluminium box. The prototype, suitable for building architectonical integration, can provide domestic hot water and electricity to the building. In order to assess the energy, economic and environmental performance of the system under different weather conditions and for diverse building uses, a suitable dynamic simulation model was developed and validated vs. experimental data. To investigate the convenience of the presented prototype and the potentiality of the developed software, a suitable case study is presented. In particular, the photovoltaic thermal collector is coupled to a stratified hot water storage tank for supplying domestic hot water to a single-family house located in three different European weather zones: Freiburg, Naples and Almeria. The system layout optimization was also performed through an energy and economic sensitivity analysis to some design and operating parameters. Useful design criteria and interesting energy and economic results were obtained.
•Development of a novel low-cost photovoltaic/thermal collector prototype.•Development of a dynamic model for thermal and electrical performance assessment.•Experimental validation of the developed simulation model.•Comparative analysis between prototype and commercial collector performance.•Case study analysis for evaluating the prototype energy and economic feasibility.
This paper describes a low-cost facile method to construct gold (Au) nanoparticles (NPs) modified copper oxide (CuO) nanowires (NWs) electrode on copper foil for the detection of glucose. Copper foil ...has been converted to aligned CuO NWs arrays by sequential formation of Cu(OH)
followed by heat treatment induced phase transformation to CuO. Au NPs are deposited on CuO NWs
simple reductive solution chemistry to impart high surface to volume ratio and enhanced catalytic activity of the resulting electrode. Structure, microstructure and morphology of Cu, Cu(OH)
NWs, CuO NWs, and Au NPs modified CuO NWs are investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The homogeneous distribution of Au NPs (average diameter ∼12 nm) on CuO NWs (average diameter 100 nm and aspect ratio ∼20) is confirmed by high-resolution transmission electron microscopy (HRTEM), scanning transmission electron microscopy (STEM) and elemental mapping. This CuO based glucose detection method gives the highest sensitivity along with the maximum linearity range. This non-enzymatic glucose sensor based on Au modified CuO NWs electrode gives broad linearity range from 0.5 μM to 5.9 mM. The sensor exhibits sensitivity of 4398.8 μA mM
cm
, lower detection limit of 0.5 μM, and very fast response time of ∼5 s. Properties of the proposed glucose sensor are also investigated in human blood and it is found that the sensor is highly accurate and reliable. In addition, higher sensitivity and lower detection limit confirm that this device is suitable for invasive detection in saliva and urine.
Abstract
With the development of the science and technology, the demanding of convenience and comfort when driving a car are getting higher and higher. As an important part that has a great influence ...on the comfort of the car driving, the car seat is also developing towards the electric direction. The electric seat is becoming the choice of more and more manufacture of automobile. However, the product quality inspection of the electric track of the car seat is still in a relatively preliminary stage. At present, the detection of the unqualified track product is mainly performed by workers listening in an anechoic room. This will lead to the high cost of construction of the anechoic chamber, low quality inspection efficiency, and instability by different quality inspection personnel. In this paper, we focus on the scraping noise detection of the electric track product, as scraping noise is the main cause of the product disqualification. Since scraping noise often features a higher energy in the high frequency band, we adopt the Short Time Fourier Transform (STFT) to acquire the total energy at different time duration. Then we model the acquired time series as summation of one sparse signal, one low-passing signal, and one noise signal. Based on the property of the three parts, the objective function is established and solved with Majorization-Minimization (MM) approach. The effectiveness of the proposed scraping detection method is verified with the real track vibration signal, and the superiority of the proposed method is verified via the comparison with other impulse detection method.
For large-scale adoption of electric vehicles (EVs), a charging network is needed near the road. The charging station planning and deployment problem should consider the increasing penetration ratio ...of EVs over a long period of time, and the highly dynamic and location-dependent demands and power grid constraints. This paper focuses on the dynamic charging network design, i.e., how to optimize the charging station locations and the number of chargers in each station at different time stages with an increasing EV penetration ratio. For each candidate location, we first model its coverage area to estimate the dynamic EV charging requirements. Then, we formulate the problem at each time stage as profit maximization, which is a mixed-integer optimization problem. To make it tractable, we investigate the profitability of candidate locations and derive their upper and lower bounds on the expected profit. Then we take two steps to transform and relax the problem to convex optimization. A fastconverging search algorithm, named RMCL-E, is proposed. Using real vehicle traces, simulation results show that the proposed algorithm can make a good trade-off between the service blocking probability and the construction cost to maximize the total profit, which is attractive for charging service providers.
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