In this paper, we revisit the problem of fusing decisions transmitted over fading channels in a wireless sensor network. Previous development relies on instantaneous channel state information (CSI). ...However, acquiring channel information may be too costly for resource constrained sensor networks. In this paper, we propose a new likelihood ratio (LR)-based fusion rule which requires only the knowledge of channel statistics instead of instantaneous CSI. Based on the assumption that all the sensors have the same detection performance and the same channel signal-to-noise ratio (SNR), we show that when the channel SNR is low, this fusion rule reduces to a statistic in the form of an equal gain combiner (EGC), which explains why EGC is a very good choice with low or medium SNR; at high-channel SNR, it is equivalent to the Chair-Varshney fusion rule. Performance evaluation shows that the new fusion rule exhibits only slight performance degradation compared with the optimal LR-based fusion rule using instantaneous CSI.
A diaphragm pump is a type of volumetric pump that has excellent sealing performance. An electromagnetic diaphragm pump is a kind of widely adopted diaphragm pump that has a simple structure, low ...power loss, and high cost performance. However, the calculation method of deformation for the electromagnetic diaphragm pump rubber diaphragm is presently lacking. Herein, a calculating method of deformation for the electromagnetic diaphragm pump rubber diaphragm is proposed. By establishing and analyzing a deformation model of the electromagnetic diaphragm pump rubber diaphragm, a theoretical relationship between the deformation of the electromagnetic diaphragm pump rubber diaphragm, the size of the electromagnetic diaphragm pump rubber diaphragm and the pressure of fluid is determined. The experimental results indicate that the biggest difference between the tested axial deformation and the calculated axial deformation of the electromagnetic diaphragm pump rubber diaphragm is 0.04 mm and the calculation results show agreement with the experimental results.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Ascertaining failure mechanism is a prerequisite of the derivation for earth pressure against retaining structures. Retaining structures constructed adjacent to existing structures and excavation ...with narrow backfill have become common in practical engineering. The backfill width has a significant effect on the failure mechanism, requiring further study. In this study, a series of discrete element analyses are conducted to investigate the shear localization in soil mass behind retaining structures with narrow backfill in the active and passive limit states at the grain scale. Furthermore, the distribution characteristic of failure surfaces in soil mass is discussed from three aspects: the development of the failure surface, the state of soil mass behind retaining structures, and the shape of the failure surface. Based on the typical nonlinear failure mechanisms observed in particle rotation contours with various backfill widths and interface friction angles, the failure mechanisms behind retaining structures with narrow spacing are categorized into three types according to the backfill widths. According to the stress characteristics of interfaces under different failure mechanisms, the variational method and Mohr stress circle analysis are adapted to analytically obtain the failure surfaces behind the retaining structure with narrow backfill. Comparisons with results obtained by the discrete element simulation show a reasonable agreement. In addition, a series of parameter studies are conducted to investigate the effect of backfill widths and interface friction angles on the failure mechanism.
Pure organic room-temperature phosphorescence (RTP), particularly from guest-host doped systems, has seen exponential growth in the last several years due to their high modulation flexibility, and ...yet challenges remain with respect to mechanistic elucidations and advantageous applications. Here we show that by constructing guest-host doped RTP systems from chiral components, namely, chiral amino compound-modified phthalimide hosts and naphthalimide guests, a chiral-selective RTP enhancement phenomenon can be observed. For example, R-enantiomeric guests in R-enantiomeric hosts produce strong red RTP afterglow while no appreciable RTP could be observed in the S-R guest-host counterpart. An unprecedented RTP intensity difference > 10
folds with the ability to distinguish an enantiomeric excess of 98% could be achieved. Temperature-dependent measurements suggest that a chirality-dependent energy transfer process may be involved in the observed phenomenon, which can be harnessed to extend the RTP application to the chiral recognition of amino compounds, such as amino alcohols.
As one of the CO2 capture and utilization technologies, Li-CO2 batteries have attracted special interest in the application of carbon neutral. However, the design and fabrication of a low-cost ...high-efficiency cathode catalyst for reversible Li2CO3 formation and decomposition remains challenging. Here, guided by theoretical calculations, CO2 was utilized to activate the catalytic activity of conventional nitrogen-doped graphene, in which pyridinic-N and pyrrolic-N have a high total content (72.65%) and have a high catalytic activity in both CO2 reduction and evolution reactions, thus activating the reversible conversion of Li2CO3 formation and decomposition. As a result, the designed cathode has a low voltage gap of 2.13 V at 1200 mA g–1 and long-life cycling stability with a small increase in the voltage gap of 0.12 V after 170 cycles at 500 mA g–1. Our work suggests a way to design metal-free catalysts with high activity that can be used to activate the performance of Li-CO2 batteries.
In-situ observation of tensile tests were performed to investigate the strengthening mechanisms of multi-walled carbon nanotube (MWCNT) reinforced Al matrix composites (AMCs). Carbon nanotubes (CNTs) ...were effectively incorporated and aligned in AMCs through a conventional powder metallurgy route. During tensile failure, the fracture process of CNTs in fabricated AMCs was clearly observed, suggesting the effective load transfer between the matrix and CNTs, and between inner walls of MWCNTs. Due to the small reinforcing effect of other factors, load transfer strengthening dominantly contributed to the observed high strengthening efficiency in CNT/Al composite, agreeing with the predicted results of the shear-lag model. This study provided evidence supporting the theory behind load transfer strengthening mechanisms of CNTs in metal matrix composites.
This paper develops efficient algorithms for distributed average consensus with quantized communication using the alternating direction method of multipliers (ADMM). We first study the effects of ...probabilistic and deterministic quantizations on a distributed ADMM algorithm. With probabilistic quantization, this algorithm yields linear convergence to the desired average in the mean sense with a bounded variance. When deterministic quantization is employed, the distributed ADMM converges to a consensus within 3+⌈log 1+δ Ω⌉ iterations where δ > 0 depends on the network topology and Ω is a polynomial fraction depending on the quantization resolution, the agents' data, and the network topology. A tight upper bound on the consensus error is also obtained, which depends only on the quantization resolution and the average degree of the graph. This bound is much preferred in large scale networks over existing algorithms whose consensus errors are increasing in the range of agents' data, the quantization resolution, and the number of agents. We finally propose our algorithm which combines both probabilistic and deterministic quantizations. Simulations show that the consensus error of our algorithm is typically less than one quantization resolution for all connected networks where agents' data can be of arbitrary magnitudes.
Electromagnetic diaphragm pump is a kind of widely applied diaphragm pump that has promising sealing performance, simple structure and low power loss. Planar pole electromagnet is a significant ...component of the electromagnetic diaphragm pump. However, the sharply changing displacement-force characteristics of the planar pole electromagnet do not match the constant load characteristics of the electromagnetic diaphragm pump. Herein, an electromagnet with variable pole area is put forward. A theoretical relationship between structural parameters, the Ampere turns and the electromagnetic force of the electromagnet with variable pole area is determined by analyzing the equivalent magnetic circuit of the electromagnet with variable pole area. The experimental results imply that the initial electromagnetic force of the electromagnet with variable pole area is 32.51% larger than the planar pole electromagnet, the engaging electromagnetic force of the electromagnet with variable pole area is 22.3% smaller than the planar pole electromagnet and the displacement-force characteristics of the electromagnet with variable pole area match the constant load characteristics of the electromagnetic diaphragm pump.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
In this work, the effects of aluminum carbide (Al4C3) on the mechanical properties and thermal behaviors of Al based composites reinforced by SiC and carbon nanotubes (CNTs) were investigated. The ...formation of Al4C3 was precisely controlled in the temperature range from 530 °C to 630 °C (80%–95% of the Al melting point) during the post heat treatment. Microscopy observations revealed that Al4C3 rods are originated from CNTs instead of SiC particles. Quantity and size of Al4C3 are highly dependent on the heat treatment temperature. It was found that the mechanical properties of the Al based composites were significantly affected by the size of Al4C3. Moreover, the formation of Al4C3 helps to decrease the coefficient of thermal expansion (CTE) of the composites due to the consumption of Al and the enhanced interfacial bonding. This study provides a potential approach for ameliorating the mechanical and thermal performances of CNTs reinforced metal matrix composites.
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The COVID-19 pandemic outbreak—as a typical emergency event—significantly has impacted employees' psychological status and thus has negatively affected their performance. Hence, along with focusing ...on the mechanisms and solutions to alleviate the impact of work stress on employee performance, we also examine the relationship between work stress, mental health, and employee performance. Furthermore, we analyzed the moderating role of servant leadership in the relationship between work stress and mental health, but the result was not significant. The results contribute to providing practical guidance for enterprises to improve employee performance in the context of major emergencies.
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