Showing papers by "Beijing University of Technology published in 2007"
TL;DR: Experiments using the AESA algorithm in handwritten digit recognition show that the new normalized edit distance between X and Y can generally provide similar results to some other normalized edit distances and may perform slightly better if the triangle inequality is violated in a particular data set.
Abstract: Although a number of normalized edit distances presented so far may offer good performance in some applications, none of them can be regarded as a genuine metric between strings because they do not satisfy the triangle inequality. Given two strings X and Y over a finite alphabet, this paper defines a new normalized edit distance between X and Y as a simple function of their lengths (|X| and |Y|) and the Generalized Levenshtein Distance (GLD) between them. The new distance can be easily computed through GLD with a complexity of O(|X| \cdot |Y|) and it is a metric valued in [0, 1] under the condition that the weight function is a metric over the set of elementary edit operations with all costs of insertions/deletions having the same weight. Experiments using the AESA algorithm in handwritten digit recognition show that the new distance can generally provide similar results to some other normalized edit distances and may perform slightly better if the triangle inequality is violated in a particular data set.
624 citations
TL;DR: In this article, an in situ TEM observation of the elastic-plastic-fracture processes of a single Si NW recorded at atomic resolution is presented, which directly shows the strain-induced structural evolution process of Si NWs and its largestrain plasticity (LSP).
Abstract: mentally. In this report, we present in situ TEM observation of the elastic-plastic-fracture processes of a single Si NW recorded at atomic resolution. The study directly shows the strain-induced structural evolution process of Si NWs and its largestrain plasticity (LSP). Our results indicate that the LSP of Si NWs via a brittle-ductile transition originates from a dislocation-initiated amorphization. This behavior is in contrast to the mechanical behavior of bulk Si. Our observation reveals a phenomenon and mechanism of the Si NW mechanics and is fundamentally important for Si-NW-based nanotechnology. The in situ Si NW elastic, elastic-plastic, and plastic deformation investigations were carried out by ultrahigh-resolution TEM (UHRTEM) by axially extending the Si NWs by means of a mechanical force created by a TEM specimen-supporting grid under electron beam irradiation, as reported in detail elsewhere [17,18] (also see the Experimental section and Sup
307 citations
TL;DR: The obtained results showed that high nitrogen removal efficiency with effluent total nitrogen below 3 mg/L could be achieved and that the nitrifying microbial communities were optimized.
Abstract: Although many studies regarding nitrogen removal via nitrite have been carried out, very limited research has been undertaken on nitrogen removal via nitrite at low temperatures. In this study, to improve the nitrogen removal efficiency from municipal wastewater, a pilot-plant of sequencing batch reactor with a working volume of 54 m3 was used to investigate nitrogen removal via nitrite from municipal wastewater at normal and low water temperature. The obtained results showed that high nitrogen removal efficiency with effluent total nitrogen below 3 mg/L could be achieved. Using real-time control with temperature ranging from 11.9 to 26.5 degrees C under normal dissolved oxygen condition (> or =2.5 mg/L), nitrogen removal via nitrite was successfully and stably achieved for a long period (180 days) with average nitrite accumulation rate above 95%. Fluorescence in situ hybridization was carried out to investigate the quantitative changes of nitrifying microbial community in the activated sludge. Fluorescence in situ hybridization results approved that the nitrifying microbial communities were optimized; ammonia oxidizing bacteria became the dominant nitrifying bacteria and nitrite oxidizing bacteria had been washed out of the activated sludge.
291 citations
TL;DR: This Letter demonstrated unusually large strain plasticity of ceramic SiC nanowires (NWs) at temperatures close to room temperature that was directly observed in situ by a novel high-resolution transmission electron microscopy technique.
Abstract: Large strain plasticity is phenomenologically defined as the ability of a material to exhibit an exceptionally large deformation rate during mechanical deformation. It is a property that is well established for metals and alloys but is rarely observed for ceramic materials especially at low temperature ( approximately 300 K). With the reduction in dimensionality, however, unusual mechanical properties are shown by ceramic nanomaterials. In this Letter, we demonstrated unusually large strain plasticity of ceramic SiC nanowires (NWs) at temperatures close to room temperature that was directly observed in situ by a novel high-resolution transmission electron microscopy technique. The continuous plasticity of the SiC NWs is accompanied by a process of increased dislocation density at an early stage, followed by an obvious lattice distortion, and finally reaches an entire structure amorphization at the most strained region of the NW. These unusual phenomena for the SiC NWs are fundamentally important for understanding the nanoscale fracture and strain-induced band structure variation for high-temperature semiconductors. Our result may also provide useful information for further studying of nanoscale elastic-plastic and brittle-ductile transitions of ceramic materials with superplasticity.
237 citations
TL;DR: In this article, local empirical likelihood-based inference for a varying coefficient model with longitudinal data is investigated, and it is shown that the naive empirical likelihood ratio is asymptotically standard chi-squared when under-moothing is employed.
Abstract: In this article local empirical likelihood-based inference for a varying coefficient model with longitudinal data is investigated. First, we show that the naive empirical likelihood ratio is asymptotically standard chi-squared when undersmoothing is employed. The ratio is self-scale invariant and the plug-in estimate of the limiting variance is not needed. Second, to enhance the performance of the ratio, mean-corrected and residual-adjusted empirical likelihood ratios are recommended. The merit of these two bias corrections is that without undersmoothing, both also have standard chi-squared limits. Third, a maximum empirical likelihood estimator (MELE) of the time-varying coefficient is defined, the asymptotic equivalence to the weighted least-squares estimator (WLSE) is provided, and the asymptotic normality is shown. By the empirical likelihood ratios and the normal approximation of the MELE/WLSE, the confidence regions of the time-varying coefficients are constructed. Fourth, when some components are o...
192 citations
TL;DR: In this article, the axial localized plasticity and super-plasticity of single-crystal beta-SiC nanowires for > 200% elongation was observed by in situ axial-tensile experiments in a scanning electron microscope.
Abstract: Super-plasticity of single-crystal beta-SiC [111] nanowires for > 200 % elongation was observed by in situ axial-tensile experiments in a scanning electron microscope. The SiC nanowires were characterized by a bamboo-like structure appearing as the 3C structured segments intergrowth along the nanowire. The axial localized plasticity and super-plasticity are suggested to result only from the 3C segments, through dislocation generation, propagation and amorphization in contrast to the highly defected structural segments that conduct elastic-deformation only, owing to the lack of slip systems. These results provide key information for understanding the mechanical behavior of SiC nanowires.
191 citations
TL;DR: In this article, Nanocubic La2Sn2O7 photocatalysts with pyrochlore structure have been successfully synthesized by a one-pot hydrothermal method.
Abstract: Nanocubic La2Sn2O7 photocatalysts with pyrochlore structure have been successfully synthesized by a one-pot hydrothermal method. The effects of alkaline concentration, reaction time, and hydrothermal temperature on the structures and morphologies of the resultant products were investigated. On the basis of characterization results from X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and selected area electron diffraction (SAED), a possible growth mechanism of the nanocubes under the hydrothermal conditions was proposed. The absorption spectra of as-prepared cubic La2Sn2O7 photocatalyst were determined by UV−vis spectrometer. Photocatalytic experiments showed that the La2Sn2O7 samples not only had a high activity for degradation of methyl orange, but also had the activity for generating H2 with a rate of 39 μmol/h under ultraviolet light irradiation.
191 citations
TL;DR: In this paper, the authors investigated the effect of cell temperature, current density and operating time on the total pressure drop in the anode and cathode parallel flow channels of an operating PEMFC.
184 citations
TL;DR: A sampling campaign of re-suspended road dust samples from 53 sites that could cover basically the entire Beijing, soil samples from the source regions of dust storm in August 2003, and aerosol samples from three representative sites in Beijing from December 2001 to September 2003, was carried out to investigate the characteristics of re suspended road dust and its impact on the atmospheric environment as mentioned in this paper.
164 citations
TL;DR: It is shown that theDenitrification potential can be substantially increased with the addition of three external carbon sources, i.e. methanol, ethanol, and acetate, and the denitrification rates of ethanol, acetate and methanl reached up to 9.6, 12, and 3.2 mgN/(g VSS x h), respectively.
Abstract: The aim of this study is to investigate the denitrification potential enhancement by addition of external carbon sources and to estimate the denitrification potential for the predenitrification system using nitrate utilization rate (NUR) batch tests. It is shown that the denitrification potential can be substantially increased with the addition of three external carbon sources, i.e. methanol, ethanol, and acetate, and the denitrification rates of ethanol, acetate, and methanol reached up to 9.6, 12, and 3.2 mgN/(g VSS·h), respectively, while that of starch wastewater was only 0.74 mgN/(g VSS·h). By comparison, ethanol was found to be the best external carbon source. NUR batch tests with starch wastewater and waste ethanol were carried out. The denitrification potential increased from 5.6 to 16.5 mg NO3-N/L owing to waste ethanol addition. By means of NUR tests, the wastewater characteristics and kinetic parameters can be estimated, which are used to determine the denitrification potential of wastewater, to calculate the denitrification potential of the plant and to predict the nitrate effluent quality, as well as provide information for developing carbon dosage control strategy.
147 citations
TL;DR: A 17alpha-ethynylestradiol (EE2)-degrading bacterium was isolated from the activated sludge of the wastewater treatment plant of an oral contraceptives producing factory in Beijing, China and on the basis of its morphology, biochemical properties and the 16S rDNA sequence analysis, this strain was identified as Sphingobacterium sp.
TL;DR: In this article, the self-assembly of polyelectrolyte multilayer membranes (PEMMs) by using dynamic layer-by-layer (LBL) adsorption technique for pervaporation separation of water/alcohol mixtures was investigated.
TL;DR: In this article, the electrical properties of manganese oxide (MnO)-doped NBBT piezoceramics were investigated using X-ray diffraction analysis.
Abstract: Microstructure and electrical properties of manganese oxide (MnO)-doped (Na0.5Bi0.5)0.92Ba0.08TiO3 (NBBT) piezoceramics were investigated in this work. X-ray diffraction analysis shows that the suitable substitution of Mn ion into the B site induces the lattice distortion of perovskite NBBT: the solution limit is at 0.3 wt% MnO. Besides, it is observed that the sintering properties can be improved by adding a small amount of MnO, thus increasing the grain size and the relative density. Further, the temperature dependence of the dielectric permittivity of NBBT ceramics indicates that the MnO addition reconstructs the disorder array destroyed by joining BaTiO3 in the Na0.5Bi0.5TiO3 system due to the sizable radius of the B-site cations. Combining these effects of MnO addition, the optimal electrical properties were acquired for NBBT ceramic with addition of 0.30 wt% MnO. The excellent electrical properties of MnO-doped NBBT ceramics indicate its promising application in large displacement actuators.
TL;DR: In this article, a successful one-step chemical synthesis of Co−Pt hollow spheres with adjustable composition was developed in an effort to explore new synthesis methods, simplify the synthesis procedure, and improve the synthetic efficiency.
Abstract: In this paper, successful one-step chemical synthesis of Co−Pt hollow spheres with adjustable composition was developed in an effort to explore new synthesis methods, simplify the synthesis procedure, and improve the synthetic efficiency. In this synthesis, a direct thermolytic reduction of platinum acetylacetonate [Pt(CH3COHCOCH3)2] and cobalt(II) acetate [Co(CH3COO)2] in refluxing ethyl glycol was explored. In the reacting mixture, an anionic surfactant sodium dodecyl sulfate (SDS) was used as the capping and structure-directing agent. These Co−Pt hollow spheres demonstrated enhanced electrocatalytic activity toward methanol oxidation in comparison with Pt nanoparticles, which is crucial for anode electrocatalysis in DMFCs.
TL;DR: In this article, a life cycle inventory (LCI) for the provision of 1 kWh of electricity to consumers in China in 2002 is presented to identify areas of improvement in the industry.
Abstract: The objective of this study was to produce detailed a life cycle inventory (LCI) for the provision of 1 kWh of electricity to consumers in China in 2002 in order to identify areas of improvement in the industry. The system boundaries were processes in power stations, and the construction and operation of infrastructure were not included. The scope of this study was the consumption of fossil fuels and the emissions of air pollutants, water pollutants and solid wastes, which are listed as follows: (1) consumption of fossil fuels, including general fuels, such as raw coal, crude oil and natural gas, and the uranium used for nuclear power; (2) emissions of air pollutants from thermal power, hydropower and nuclear power plants; (3) emissions of water pollutants, including general water waste from fuel electric plants and radioactive waste fluid from nuclear power plants; (4) emissions of solid wastes, including fly ash and slag from thermal power plants and radioactive solid wastes from nuclear power plants. Data were collected regarding the amount of fuel, properties of fuel and the technical parameters of the power plants. The emissions of CO2, SO2, NOx, CH4, CO, non-methane volatile organic compound (NMVOC), dust and heavy metals (As, Cd, Cr, Hg, Ni, Pb, V, Zn) from thermal power plants as well as fuel production and distribution were estimated. The emissions of CO2 and CH4 from hydropower plants and radioactive emissions from nuclear power plants were also investigated. Finally, the life cycle inventory for China’s electricity industry was calculated and analyzed. Related to 1 kWh of usable electricity in China in 2002, the consumption of coal, oil, gas and enriched uranium were 4.57E-01, 8.88E-03, 7.95E-03 and 9.03E-08 kg; the emissions of CO2, SO2, NOx, CO, CH4, NMVOC, dust, As, Cd, Cr, Hg, Ni, Pb, V, and Zn were 8.77E-01, 8.04E-03, 5.23E-03, 1.25E-03, 2.65E-03, 3.95E-04, 1.63E-02, 1.62E-06, 1.03E-08, 1.37E-07, 7.11E-08, 2.03E-07, 1.42E-06, 2.33E-06, and 1.94E-06 kg; the emissions of waste water, COD, coal fly ash, and slag were 1.31, 6.02E-05, 8.34E-02, and 1.87E-02 kg; and the emissions of inactive gas, halogen and gasoloid, tritium, non-tritium, and radioactive solid waste were 3.74E+01 Bq, 1.61E-01 Bq, 4.22E+01 Bq, 4.06E-02 Bq, and 2.68E-10 m3 respectively. The comparison result between the LCI data of China’s electricity industry and that of Japan showed that most emission intensities of China’s electricity industry were higher than that of Japan except for NMVOC. Compared with emission intensities of the electricity industry in Japan, the emission intensities of CO2 and Ni in China were about double; the emission intensities of NOx, Cd, CO, Cr, Hg and SO2 in China were more than 10 times that of Japan; and the emission intensities of CH4, V, Pb, Zn, As and dust were more than 20 times. The reasons for such disparities were also analyzed. To get better LCI for the electricity industry in China, it is important to estimate the life cycle emissions during fuel production and transportation for China. Another future improvement could be the development of LCIs for construction and operation of infrastructure such as factory buildings and dams. It would also be important to add the information about land use for hydropower.
TL;DR: In this paper, the performance of perovskite-type oxides in the combustion of ethylacetate (EA) has been evaluated using the citric acid complexing-hydrothermal-coupled method.
TL;DR: In this article, the development of high current-density cathodes employing scandia-doped tungsten powders is reviewed, and the performance of these cathodes is attributed to a surface multilayer of Ba-Sc-O of about 100-nm thickness that uniformly covers the W grains with nanometer-size particles distributed on the growth steps.
Abstract: The development of high current-density cathodes employing scandia-doped tungsten powders is reviewed in this paper. A matrix with a submicrometer microstructure characterized by uniformly distributed nanometer particles of scandia is believed to play a dominant role in the improved emission capability of these cathodes. Space-charge-limited current densities of over 30 A/cm2 at 850 degCb have been repeatedly obtained for many runs of cathodes fabricated from the different batches of scandia-doped tungsten powders. A lifetime of over 10000 h at 950-degCb 2-A/cm2 dc loading in a test diode has been achieved. Periodic high current-density pulse testing was also carried out during the test. The performance for both the dc and pulsed current densities remained stable. When tested at Stanford Linear Accelerator Center in a cathode life test vehicle with a Pierce gun configuration, the cathode operated for 500 h at 1170 degC b, with a pulsed loading of 100 A/cm2 and with less than 5% degradation in current density. The outstanding performance of these cathodes is attributed to a surface multilayer of Ba-Sc-O of about 100-nm thickness that uniformly covers the W grains with nanometer-size particles distributed on the growth steps. The layer is formed after proper activation by diffusion of free or ionic Sc together with Ba and O from the interior of the cathode to its surface. This highly mobile, free, or ionic Sc is liberated from constituents produced during impregnation and activation by reactions between the matrix materials and impregnants
TL;DR: In this article, an integrated MM5-CMAQ modeling approach was employed to investigate the PM 10 air pollution issue in Beijing, China, with a focus on assessing pollution contributions from surrounding provinces.
TL;DR: In this article, a groupwise empirical likelihood procedure was proposed to handle the inter-series dependence for the longitudinal semiparametric regression model, and employed bias correction to construct the empirical likelihood ratio functions for the parameters of interest.
Abstract: A semiparametric regression model for longitudinal data is considered. The empirical likelihood method is used to estimate the regression coefficients and the baseline function, and to construct confidence regions and intervals. It is proved that the maximum empirical likelihood estimator of the regression coefficients achieves asymptotic efficiency and the estimator of the baseline function attains asymptotic normality when a bias correction is made. Two calibrated empirical likelihood approaches to inference for the baseline function are developed. We propose a groupwise empirical likelihood procedure to handle the inter-series dependence for the longitudinal semiparametric regression model, and employ bias correction to construct the empirical likelihood ratio functions for the parameters of interest. This leads us to prove a nonparametric version of Wilks' theorem. Compared with methods based on normal approximations, the empirical likelihood does not require consistent estimators for the asymptotic variance and bias. A simulation compares the empirical likelihood and normal-based methods in terms of coverage accuracies and average areas/lengths of confidence regions/intervals.
TL;DR: A comprehensive study of the performance of typical headway distribution models on urban freeways is presented and shows that the double-displaced negative exponential distribution model provided the best fit to these urban freeway headway data, especially for HOV lanes at wideranging flow levels.
Abstract: Vehicle headway distribution is fundamental for several important traffic research and simulation issues. Many headway models have been developed over the past decades. Each has its own strength and weakness. Selection of the most suitable model for a certain traffic condition remains an open issue. A comprehensive study of the performance of typical headway distribution models on urban freeways is presented. With the advanced loop event data analyzer system, many accurate headway observations were obtained from I-5 in the area of Seattle, Washington. These headway data were used to calibrate and examine the performance of various headway models. The goodness of fit for several most commonly used headway distribution models was investigated by using headways observed on regular lanes and high-occupancy-vehicle (HOV) lanes from different time periods of day. To evaluate the performance of these headway models, the analytical Kolmogorov-Smirnov test statistic and visualized comparison curves were used to me...
TL;DR: An integrated approach combining offline precomputation of optimal candidate paths with online path retrieval and dynamic adaptation is proposed for a dynamic navigation system in a centralized system architecture based on a static traffic data file.
Abstract: In this paper, an integrated approach combining offline precomputation of optimal candidate paths with online path retrieval and dynamic adaptation is proposed for a dynamic navigation system in a centralized system architecture. Based on a static traffic data file, a partially disjoint candidate path set is constructed prior to the trip using a heuristic link weight increment method. This method satisfies reasonable path constraints that meet the drivers' preferences, as well as alternative path constraints, that limit the joint failure probability for candidate paths. The characteristics of the proposed algorithm are the following: 1) The response time for online navigation demand is nearly linear with network size and less dependent on system load; 2) the veracity of the pretrip route plan based on the static data file is improved by taking travel time reliability into account; and 3) system optimization can be approximated without sacrificing driver preferences. The algorithm is tested on randomly generated road networks, and the numerical results show the efficiency of the approach
29 Oct 2007
TL;DR: This paper proposes to locate and track a drivers' mouth movement using a CCD camera to study on monitoring and recognizing a driver's yawning and shows that Gabor coefficients are more powerful than geometric features to detect yawning.
Abstract: Fatigue driving is an important reason of traffic accidents. Yawning is an evidence of driver fatigue. This paper proposes to locate and track a driver's mouth movement using a CCD camera to study on monitoring and recognizing a driver's yawning. Firstly detecting drivers' faces uses Gravity-Center template, then detecting drivers' left and right mouth corners by grey projection, and extracting texture features of drivers' mouth corners (left and right) using Gabor wavelets. Finally LDA is applied to classify feature vectors to detect yawning. The method is tested on 400 images from twenty videos. In contrast, yawning is also detected by the ratio of mouth height and width. The experiment results show that Gabor coefficients are more powerful than geometric features to detect yawning and the average recognition rate is 95% which has more than 20% improvement.
TL;DR: In this paper, the effect of Li2CO3 addition on the dielectric and piezoelectric responses in 0.5PZN-O3 systems was systematically studied.
Abstract: Low-temperature sintering of 0.5Pb(Zn1∕3Nb2∕3)O3–0.5Pb(Zr0.47Ti0.53)O3 ceramics (0.5PZN–0.5PZT) was investigated using Li2CO3 as sintering aids. The addition of Li2CO3 significantly improved the sinterability of 0.5PZN–0.5PZT ceramics, resulting in a reduction of sintering temperature from 1100to950°C. Moreover, the effect of Li2CO3 addition on the dielectric and piezoelectric responses in 0.5PZN–0.5PZT systems was systematically studied in this work. The analysis of x-ray diffraction patterns and scanning electron microscopy indicated that the solubility limit of Li ions in perovskite structures was near 0.5wt% in Li2CO3 form. Below the solubility limit, Li+ ions entered the six-fold coordinated B sites of oxygenic octahedral center and enhanced the compositional fluctuation in nanoscale, resulting in the increase of the degree of diffuseness γ. While at high doping level above the solubility limit, γ decreased subsequently, which was attributed to the formation of pyrochlore phase. Raman analysis on the...
TL;DR: In this paper, a step-feed sequencing batch reactor (SBR) was used for the study of nitrogen removal from real municipal wastewater, which achieved advanced and enhanced nitrogen removal by three phases of consecutive aerobic and anoxic periods and also three steps of feeding, combined with real time control.
TL;DR: It was found that Beijing needs to take continual emission control efforts to comprehensively improve its air quality to the Class II level by 2008 and possible future PM"1"0 concentration distributions in 2008 through two proposed emission sources reduction strategies.
Abstract: A coupled MM5-ARPS-CMAQ air quality modeling system was applied for investigating the contributions of various emission sources to the ambient concentrations of PM"1"0 in the Beijing metropolitan region of China. A three-level nested simulation domain was established for facilitating the modeling study, and a GIS-based atmospheric pollutant emission database was constructed to provide important emission information for the Models-3/CMAQ model. After verification, the coupled modeling system was implemented to predict the hourly contribution ratios of various PM"1"0 emission sources to Beijing's air quality during four representative months of January, April, August and October in the base year of 2002. It was found from the modeling results that three major sources (including fugitive industrial emissions, construction sites, and road dusts) presented a relatively high contribution to the PM"1"0 pollution in Beijing, with the contribution ratios of 28.67%, 42.88%, 42.46% and 35.67% for spring, summer, autumn and winter, respectively. In addition, the impacts of emissions from two major industrial zones within Beijing on its air quality were quantified. Moreover, the coupled modeling system was applied to explore possible future PM"1"0 concentration distributions in 2008 through two proposed emission sources reduction strategies. It was found that Beijing needs to take continual emission control efforts to comprehensively improve its air quality to the Class II level by 2008. The modeling results could provide sound decision making basis for developing effective air quality management strategies in the planning region.
TL;DR: Users and businesses alike get to turn their raw data into new science, technology, and money.
Abstract: Users and businesses alike get to turn their raw data into new science, technology, and money.
TL;DR: In this article, a shear strain based multiaxial fatigue damage parameter was proposed by von Mises criterion based on combining the maximum shear strains and the normal strain excursion between adjacent turning points of the maximum strain on the critical plane.
TL;DR: In this paper, La-doped ZnO films were prepared by RF magnetron sputtering using different composition powder compacted targets (0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 38, 39, 40, 41, 42, 43, 46, 46
TL;DR: A quasi-secure quantum dialogue protocol using single photons, which uses batches of single photons which run back and forth between the two parties to increase the efficiency of information transmission.
Abstract: A quasi-secure quantum dialogue protocol using single photons was proposed. Different from the previous entanglement-based protocols, the present protocol uses batches of single photons which run back and forth between the two parties. A round run for each photon makes the two parties each obtain a classical bit of information. So the efficiency of information transmission can be increased. The present scheme is practical and well within the present-day technology.
TL;DR: In order to improve the energy separate efficiency of vortex tubes, three innovative technologies were applied to vortex tubes in this article, including a new nozzle with equal gradient of Mach number and a new intake flow passage of nozzles with equal flow velocity.
Abstract: Vortex tube (VT) is a simple energy separating device which is compact and simple to produce and to operate. Although intensive research has been carried out in many countries over the years, the efficiency is still low. In order to improve the energy separate efficiency of vortex tubes, three innovative technologies were applied to vortex tubes. A new nozzle with equal gradient of Mach number and a new intake flow passage of nozzles with equal flow velocity were designed and developed to reduce the flow loss. A new kind of diffuser invented by us was installed for reducing friction loss of air flow energy at the end of the hot end tube of vortex tube, which can greatly improve the performance of vortex tube. The experiment results indicated that these modifications could remarkably improve the performance of vortex tube. The developed vortex tube was not only superior to the conventional vortex tube but also superior to that made by two companies in world under big cold gas mass flow ratio.