中回盐炉超温防爆问题

我厂热处理中回盐炉原加工零件其硬度指标只能达到>HRC40,而对于要求在HRC35左右的一般零件难以达到,为满足指标要求,必须改变盐炉所用盐份,在即采用50％KNO_3+30％NaNO_3,这样,炉温要比原先炉温高得多,对硝盐炉而言,炉温度,有一定危险性,据热处理手册要求,

A three-year longitudinal study of the relation between left atrial diameter remodeling and atrial fibrillation ablation outcome

Background The long-term prognostic influence of left atrial diameter （LAD） remodeling on the status of post-radiofrequency catheter ablation （RI CA） atrial fibrillation （AF） is unclear. This study employed a two-stage model from 3-year echocardiographic data to ascertain whether the two-stage model predicts RFCA outcome more favorably than models using the baseline LAD. Methods Data were retrospectively collected from 263 consecutive patients with drug-refractory AF undergoing RFCA. Regular echocardiographic measurements of LAD were performed at baseline, 1, 3, 6, and 12 months and then every 6 months after RFCA. Sex, age, type of AF, number of RFCA, and AF status were recorded. We obtain the actual （predicted） 3-year LAD using a longitudinal linear mixed model （1st stage）. Logistic regression models based on the baseline LAD （Model 1）, actual （predicted） 3-year LAD （Model 2） （2nd stage）, and observed 3-year LAD （Model 3） were constructed to predict RFCA outcome. The area under the receiver operating characteristic curve （AUC） were used to assess the performance of models. Results The lowess smoothed curve indicated that the LAD declined over the first three months and remained stable up to 36 months after RFCA. The degree of LAD reduction was significantly influenced by the baseline LAD. Non-paroxysmal AF, large LAD and female gender were significant predictors of AF recurrence. Model 2 had the largest AUC among the three models. Conclusions This longitudinal study-based two-stage model outperforms the original logistic model using the baseline LAD. Non-paroxysmal AF, larger LAD and female gender are significant predictors of RFCA failure.

Biomarkers and potential pathogenesis of colorectal cancer-related ischemic stroke

AIM To investigate the specific biomarkers and potential pathogenesis of colorectal cancer-related ischemic stroke(CRCIS).METHODS A retrospective study was conducted on CRCIS patients(colorectal cancer patients with ischemic stroke without conventional stroke risk factors) registered at seven centers between January 2007 and December 2017. Clinical data and laboratory and imaging findings were compared with age-and sex-matched patients with colorectal cancer(CRC) without ischemic stroke that were admitted to the same hospital during the same period. Univariate and multivariate analyses were performed to analyze the independent risk factors for CRCIS. A receiver operator characteristic curve was configured to calculate the optimal cut-off value of the products of the independent risk factors for CRCIS. RESULTS A total of 114 CRCIS patients and 114 CRC patients were included. Multiple lesions in multiple vascular territories were common in CRCIS patients(71, 62.28%). The levels of plasma D-dimer, carcinoembryonic antigen(CEA), cancer antigen 125, and neutrophil count were significantly higher in CRCIS patients than in CRC patients. Multiple logistic regression analysis revealed that plasma D-dimer levels [odds ratio(OR) = 1.002, 95% confidence interval(CI): 1.001-1.003, P < 0.001], CEA levels(OR = 1.011, 95%CI: 1.006-1.015, P < 0.001), and neutrophil count levels(OR = 1.626, 95%CI: 1.268-2.087, P < 0.001) were independent risk factors for CRCIS. In addition, receiver operator characteristic curve revealed that the area under curve for the products of plasma D-dimer, CEA, and neutrophil count was 0.889 ± 0.022(95%CI: 0.847-0.932, P < 0.001), and the optimal cut-off value for the product was 252.06, which was called the CRCIS Index, with a sensitivity of 86.0% and specificity of 79.8%.CONCLUSION Hypercoagulability induced by elevated CEA and neutrophils may be an important cause of CRCIS. The CRCIS index, which serves as a biomarker of CRCIS, needs further study.

TCP-Rab： a receiver advertisement based TCP protocol

With the evolution of network technologies, the deficiencies of TCP protocol are becoming more and more distinct. The new TCP implementation, called Receiver Advertisement Based TCP (TCP-Rab) proposed here to eliminate these deficiencies, adopts two basic mechanisms: (1) Bandwidth Estimation and (2) Immediate Recovery. Bandwidth estimation is carried out at the receiver, and the result is sent back to the sender via the acknowledgments. Immediate Recovery guarantees high performance even in lossy link. Rab can distinguish the reason for packet loss, and thus adopt appropriate recovery strategy. For loss by network congestion, it will back off its congestion window, and for loss by link errors, it will recover the congestion window immediately. Simulations indicated that Rab has superiority over other TCP implementations.

8-Weighted-Type Fractional Fourier Transform Based Three-Branch Transmission Method

To improve the bit error rate(BER) performance of multiple input multiple output(MIMO) systems with low complexity, a three-branch transmission scheme employing 8-weighted-type fractional Fourier transform(8-WFRFT) module is proposed. In the proposed scheme, the original signal is first decomposed into eight sub-signals and then merged into three component signals by the same carrier pattern. The three signals have mathematical constraint relations among themselves that can counteract the channel fading. They are simultaneously transmitted via three independent antennas after delay regulating. At the receiver, an inverse 8-WFRFT module is employed to obtain the estimated original signal by processing the received signal. Then, the bit error rate(BER) performance, transmitting power, transmission rate, power spectrum and computational complexity of the proposed scheme are analysed in detail. Numerical results show that the proposed scheme has a superior performance compared to STBC based three-antenna transmission scheme, in terms of BER performance.

Joint Non-Orthogonal Multiple Access (NOMA) & Walsh-Hadamard Transform: Enhancing the Receiver Performance

Non-orthogonal multiple access(NOMA) is a new access method to achieve high performance gains in terms of capacity and throughput, so it is currently under consideration as one of the candidates for fifth generation(5 G) technologies. NOMA utilizes power domain in order to superimpose signals of multiple users in a single transmitted signal. This creates a lot of interference at the receive side. Although the use of successive interference cancellation(SIC) technique reduces the interference, but to further improve the receiver performance, in this paper, we have proposed a joint Walsh-Hadamard transform(WHT) and NOMA approach for achieving better performance gains than the conventional NOMA. WHT is a well-known code used in communication systems and is used as an orthogonal variable spreading factor(OVSF) in communication systems. Application of WHT to NOMA results in low bit error rate(BER) and high throughput performance for both low and high channel gain users. Further, it also reduces peak to average power ratio(PAPR) of the user signal. The results are discussed in terms of comparison between the conventionalNOMA and the proposed technique, which shows that it offers high performance gains in terms of low BER at different SNR levels, reduced PAPR, high user throughput performance and better spectral efficiency.

Theoretical Investigation on Internal Leakage and Its Effect on the Efficiency of Fluid Switcher-Energy Recovery Device for Reverse Osmosis Desalting Plant

This work is focused on the theoretical investigation of internal leakage of a newly developed pi lotscale fluid switcherenergy recovery device （FSERD） for reverse osmosis （RO） system. For the purpose of in creasing FSERD efficiency and reducing the operating cost of RO, it is required to control the internal leakage in a low level. In this work, the internal leakage rates at different leakage gaps and retentate brine pressures are investigated by computational fluid dynamics （CFD） method and validating experiments. It is found that the internal leak age has a linear relationship with the retentate brine pressure and a polynomial relationship with the scale of leakage gap. The results of the present work imply that low internal leakage and high retentate brine pressure bring benefits to achieve high FSRD efficiency.

Contrastive analysis and crashworthiness optimization of two composite thin-walled structures

For the safety protection of passengers when train crashes occur, special structures are crucially needed as a kind of indispensable energy absorbing device. With the help of the structures, crash kinetic-energy can be completely absorbed or dissipated for the aim of safety. Two composite structures(circumscribed circle structure and inscribed circle structure) were constructed. In addition, comparison and optimization of the crashworthy characteristic of the two structures were carried out based on the method of explicit finite element analysis(FEA) and Kriging surrogate model. According to the result of Kriging surrogate model, conclusions can be safely drawn that the specific energy absorption(SEA) and ratio of specific energy absorption to initial peak force(REAF) of circumscribed circle structure are lager than those of inscribed circle structure under the same design parameters. In other words, circumscribed circle structure has better performances with higher energy-absorbing ability and lower initial peak force. Besides, error analysis was adopted and the result of which indicates that the Kriging surrogate model has high nonlinear fitting precision. What is more, the SEA and REAF optimum values of the two structures have been obtained through analysis, and the crushing results have been illustrated when the two structures reach optimum SEA and REAF.

Impact of Phase Noise on TDMS Based Calibration for Spaceborne Multi-Beam Antennas

For spaceborne multi-beam antennas(MBAs), time division multiplexed switching(TDMS) based calibration receiver can reduce implementation costs effectively and is very suitable for large-scale applications. However, in practice, random phase noise imposed by noisy local oscillators can cause significant performance degradation in TDMS-based calibration systems. Characterization of phase noise effects is therefore crucial for practical applications. In this paper, we analyze the impact of phase noise on the calibration performance for a MBA system. Specifically, we derive the relationship between the probability of correct amplitude/phase estimation and various practical factors involving the signal-to-noise ratio(SNR), the standard deviation of phase noise, the given tolerance region, and the length of the spreading code. The results provide high efficiency for evaluating the calibration performance of the MBAs based on TDMS, especially for precisely anticipating the impact of phase noise. Finally, the accuracy of the derived results is assessed by simulations in different scenarios.

THE CONFIDENCE EVALUATION FOR AIRBORNE GPS DATA

GPS kinematic carrier phase measurements can be used to determine seven di- mension state and three attitude parameters of a motional carrier,such as an aircraft or a low- earth-orbit spacecraft,on which an antenna is installed to receive GPS signals. It is known from airborne GPS test results for photogrammetry in China since 1994 that GPS carrier phase measurements in a motional environment have acquired external accuracies of ± 7. 9cm for two dimensional positions and ± 18. 1cm for point heights. This paper describes airborne GPS carrier phase -measurements with multireference stations and discusses how to evaluate the confidence of GPS kinematic data.

Asymptotic Analysis for Low-Resolution Massive MIMO Systems with MMSE Receiver

The uplink achievable rate of massive multiple-input-multiple-output(MIMO) systems, where the low-resolution analog-to-digital converters(ADCs) are assumed to equip at the base station(BS), is investigated in this paper. We assume that only imperfect channel station information is known at the BS. Then a new MMSE receiver is designed by taking not only the Gaussian noise, but also the channel estimation error and quantizer noise into account. By using the Stieltjes transform of random matrix, we further derive a tight asymptotic equivalent for the uplink achievable rate with proposed MMSE receiver. We present a detailed analysis for the number of BS antennas through the expression of the achievable rates and validate the results using numerical simulations. It is also shown that we can compensate the performance loss due to the low-resolution quantization by increasing the number of antennas at the BS.

Advances in Cadaverine Bacterial Production and Its Applications

Cadaverine. a natural polyamine with multiple bioactivities that is widely distributed in prokaryotes and eukaryotes, is becoming an important industrial chemical. Cadaverine exhibits broad prospects for various applications, especially as an important monomer for bio-based polyamides. Cadaverine-based polyamide PA 5X has broad application prospects owing to its environmentally friendly characteristics and exceptional performance in water absorption and dimensional stability. In this review, we summarize recent findings on the biosynthesis, metabolism, and physiological function of cadaverine in bacteria, with a focus on the regu- latory mechanism of cadaverine synthesis in Escherichia coil （E. coli）. We also describe recent developments in bacterial production of cadaverine by direct fermentation and whole-cell bioconversion, and recent approaches for the separation and purification of cadaverine. In addition, we present an overview of the ap- plication of cadaverine in the synthesis of completely bio-based polyamides. Finally. we provide an outlook and suggest future developments to advance the production of cadaverine from renewable resources.

Extracting Acoustic Source Information of Shipping Noise for Dynamic Ambient Noise Modelling

Shipping traffic is one of the largest contributors to anthropogenic noise in the ocean. Noise generated by merchant ships elevates natural occurring ambient noise level by 20-30 dB in many areas of the world＇s ocean. In order to model the contributions of the noise generated by merchant ships to underwater ambient noise level correctly, a database that consists of the source levels as a function of frequency for different types of ships is essential. This paper describes the conceptual design, with an emphasis on the characteristics of shipping noise as sound sources, of a marine noise database. It was developed for providing necessary parameters for underwater ambient noise modelling. The parameters relevant to shipping noise modelling are organized in two catalogues： （l） source-receiver geometry related parameters, namely the coordinates of the ships at a given time period, as well as the sizes/types of the ships from which the noise source depths may be derived, and （2） acoustically relevant parameters, i.e., the acoustic SLs （source levels） at given frequencies. An example is presented here to demonstrate the efficacy of this database. The study area is a 117 × 55 km2 region off the coast of La Spezia, Italy, in the Mediterranean Sea.

Selection of Heat Recovery Ventilators in Different Climate Zones of China

Considering four different climate zones in China, an investigation on the choice of heat recovery ventilator for the buildings with little moisture emissions is carried out. The annual composition of energy consumption of air intake for per unitary air ventilation flow rate is evaluated by employing the testing data of climatic parameters in eight selected cities. The analysis shows that the total heat recovery is suitable in a controlled ventilation system with air humidity controlled during heating period of all the climates. For the building without air humidity controlled in winter, the sensible heat recovery ventilators can be used in severe cold and cold regions, and total heat recovery systems are more suitable for energy saving in hot summer and cold winter and hot summer and warm winter regions.

Prognostic Biomarkers in Patients with Ischemic Stroke Who Received Thrombolytic Therapy

Background： The aim of the research was to evaluate the association between CRP （C-reactive protein）, troponin I, d-dimer, creatinine, glucose, GFR （glomerular filtration rate） and LDL-C （low-density lipoprotein cholesterol） levels at the admission and the results of thrombolytic therapy. Materials and methods： 113 patients who underwent thrombolytic therapy for acute ischemic stroke in Pauls Stradins Clinical University Hospital from 01.01.2015 to 01.01.2016 were studied retrospectively. Blood samples were collected in the emergency department. The neurological status was estimated using the NIHSS （National Institute of Health Stroke Scale）. The efficacy of thrombolytic therapy was assessed by comparing NIHSS score at the admission and after treatment. Afterward all patients were divided into three groups-the major improvement （NIHSS 〉 4）, minor improvement （NIHSS ≤ 4） and without any clinical effect. Results： Only the median levels of GFR were significantly （p = 0.015） lower in patients who did not have any clinical improvements after thrombolytic therapy as compared to patients with the major or minor improvements （60.0, IQR （interquartile range） 42.4-72.3 mL/min/1.73m2; 83.2, IQR 65.3-98.3 mL/min/1.73m2 and 75.9, IQR 59.2-94.6 mL/min/1.73m2）. Based on the ROC （receiver operating characteristic） curve, the optimal cut-off value of GFR level as an indicator for prediction of worsen clinical outcome after thrombolytic therapy was projected to be 61.65 mL/min/1.73m2, which yielded a sensitivity of 71.4% and a specificity of 24.5%, the area under the curve was 0.788 （95% CI （confidence interval）, 0.648-0.928）. According Spearman rank correlation test was founded statistically significant indirect correlation between GFR level and NIHSS score after treatment （r = -0.410, p = 0.020） in patients with severe stroke （NIHSS 〉 14）. Conclusions： GFR level lower than 61.65 mL/min/1.73m2 at the admission could predict as a worse outcome, especially in patients with severe stroke.

A Robust Decision Feedback Equalizer for ATSC DTV Receivers

Least mean square (LMS) decision feedback equalizer (DFE) is preferred as an effective solution to coping with inter-symbol interference (ISI) for ATSC digital television (DTV) receivers. In DTV transmission environment, echo delay often covers several hundreds symbols, which leads to very large-scale equalizer. One consequence of the large-scale equalizer is the very slow convergence, which combined with error propagation, inherent drawback of DFE, seriously deteriorates the performance of the receivers, especially in severe channels More working modes and corresponding robust control mechanism were given to help the equalizer converge to the stable state smoothly. Simulation results show that the improved equalizer can perform better, especially in the severe channels.

Consumer willingness to pay for plastic bags levy and willingness to accept eco-friendly alternatives in Botswana

Plastic bags, though commonly used for packaging of goods, are highly durable and non- biodegradable. Plastic bag litter serves as a negative environmental externality detrimental to animal health and natural beauty of the environment. In an effort to curtail the excessive use of plastic bags in Botswana, the government introduced a plastic levy targeted at consumers at retail points. This study uses primary data collected from 367 respondents randomly selected from six geospatially and purposively selected shopping malls to determine the consumers＇ willingness to pay （WTP） for continued plastic bag usage and their willingness to accept （WTA） to shift to eco-friendly alternatives. The results of the study revealed that open dumping and burning of plastic litter are more common in Maun than in Gaborone, It also showed that there is a significant relationship between the level of education and W＇FP. Further, there is a significant variation in income and education in respect to environmental awareness. The government should improve its efforts of sensitizing the public about the improper disposal of plastic bags.

Optimizing Low-Temperature Heat Recovery in a Refinery Fluid Catalytic Cracking Unit Based on Pinch Analysis

In this paper, the research was focused on optimizing low-temperature heat recovery to adopt multi-effect distil- lation （MED） in desalination by pinch technology. And further analysis indicated that phase changes occurred during the heat recovery process. In such case, the feed stream was divided into two streams： the liquid feed stream and the gaseous feed stream. Through calculation, the optimal ATmin was established at 26℃, and the total cost of heat exchange process was only $1.098× 106. By using the Problem Table Algorithm for pinch analysis, the temperature of the hot and the cold steams was 119℃ and 93 ℃, respectively. At a temperature higher than 119 ℃, all heat of the hot stream could not be cooled by the condenser, and the minimum heat load of utility （QH.min） was 440457.64 kW; and at a temperature below 93 ℃, all heat of the cold stream could not be provided by the heater, and the minimum cold load of utility （QC.min） was 1965993.85 kW. Finally, the synthesis of heat exchanger network was established through integrating two heat exchanger networks.

Distributed Solar PV System for Industrial Application

The paper presents the design and field test of a distributed solar PV system for industrial application （DGPVi）. DGPVi utilizes HyPV （hybrid PV） system which generates solar power for self-consumption in lighting and air conditioning in a production line of a factory when solar energy is available. It does not feed the excess PV power to the grid. HyPV will be switched to grid power supply when solar energy is not available. A 3 kWp DGPVi is installed in a factory for field demonstration. The test results show that the solar PV power generated can be utilized immediately. The solar energy generation efficiency （kWh/day per kWp PV installation） of DGPVi is close to that of grid-tied PV system without self-consumption and battery storage. The yearly return on investment of DGPVi is 2.0% at the present installation cost or 3.3% at further cost-down cost. The payback time will be 14.3 years at the present installation cost or 12.1 years at cost-down cost. The present study verifies the economic feasibility of DGPVi.

Hydrogen Isotopes Recovery from Liquid Lithium under Dynamic Conditions

In the IFMIF （International Fusion Materials Irradiation Facility）, high-intensity deuteron ion beam is targeted at flowing liquid Li to produce neutron for long-time irradiation test of fusion materials. Radioactive tritium （T） will be produced as by-product of the D-Li reaction. Y hot trap is expected as an effective system to recover T from the liquid Li target loop. In the present study, absorption behavior of hydrogen isotopes in Y plates is experimentally and analytically investigated under stirring conditions of liquid Li. Experiments clarified that H2 absorption rates of solid Y immersed in Li are independent of the rotating rate in the range of 0 to 100 rpm and are in proportion to the inlet H2 concentration. The rate-determining step is H diffusion in Y. A mass-transfer coefficient is a useful parameter to correlate the overall H transfer from the gaseous phase through liquid Li to the solid Y plate. The effect of activation temperature on the overall performance when Y absorbs H is comparatively investigated. It is considered that heating at 673 K is effective to activate Y along with HF treatment.