The Domain Decomposition Method(DDM) is a powerful approach to solving maily types of PDE's. DDM is especially suitable for massively Parallel computers. In the past, most research on DDM has focused on the domain...The Domain Decomposition Method(DDM) is a powerful approach to solving maily types of PDE's. DDM is especially suitable for massively Parallel computers. In the past, most research on DDM has focused on the domain splitting technique. In this paper. we focus our attention on use of a combination of techniques to solve each subproblem. The central question with DDM is that of how to doal with the pseodoboundary conditions. Here, we introduce a set of operators which act on the pseudo-boundaries in the solution process, referring to this new. procedure as the 'Generalized Domain Decomposition A.Jlethod(GDDM).' We have already obtained convergence factors for GDDM with certain classes of PDE's. These ctonvergence factors show that we can derive exact solutions of the whole problem for certain types of PDE's, and can get superior speed of convergence for other types.展开更多
[Objectives]The extraction conditions of formula oolong tea were investigated by an orthogonal experiment.[Methods]The technical conditions were optimized by the 4C method,and the application of formula oolong tea ext...[Objectives]The extraction conditions of formula oolong tea were investigated by an orthogonal experiment.[Methods]The technical conditions were optimized by the 4C method,and the application of formula oolong tea extract in cigarettes was studied.[Results]①In the experimental range,the best sensory evaluation effect of formula oolong tea extract was obtained with extraction conditions of 70%ethanol as extraction solvent,extraction time h,extraction temperature 25℃,and ultrasonic frequency 80 kHz,and follow-up low-temperature concentration,low-temperature sedimentation and low-temperature centrifugation.②The effects of different centrifugal speeds on the quality of formula oolong tea extract were explored.The formula oolong tea extract obtained under the conditions of 3000 r/min and centrifugal time of 10 min showed the best evaluation effect with soft and delicate smoke,rich smoke fragrance,good comfort and refreshing mouthfeel.③The effective aroma components in the formula oolong tea extract were qualitatively analyzed by GC-MS.[Conclusions]This study provides high-quality raw materials and a theoretical basis for the research of independent flavor blending in cigarette industry enterprises.展开更多
The thermal decomposition processes of ephedrini hydrochloridum and its kinetics are studied by TG-DTG techniques. A combined method, which includes Achar method, Coats-Redfera method, and Ozawa method, is put forward...The thermal decomposition processes of ephedrini hydrochloridum and its kinetics are studied by TG-DTG techniques. A combined method, which includes Achar method, Coats-Redfera method, and Ozawa method, is put forward for determining kinetic model under non-isothermal conditions. By applying the combined method, it is determined that the thermal decomposition of ephedrini hydrochloridum is subjected to cylindrical symmetric diffusion. And the reaction function isƒ(α)=2(1-α)?, apparent activation energy (115.26±3.55) kJ·mol−1, pre-exponential factor 4.62×108 s−1. Results show that the combined method is feasible and simple.展开更多
Diffusions of multiple components have numerous applications such as underground water flow, pollutant movement, stratospheric warming, and food processing. Particularly, liquid hydrogen is used in the cooling process...Diffusions of multiple components have numerous applications such as underground water flow, pollutant movement, stratospheric warming, and food processing. Particularly, liquid hydrogen is used in the cooling process of the aeroplane. Further, liquid nitrogen can find applications in cooling equipment or electronic devices, i.e., high temperature superconducting(HTS) cables. So, herein, we have analysed the entropy generation(EG), nonlinear thermal radiation and unsteady(time-dependent) nature of the flow on quadratic combined convective flow over a permeable slender cylinder with diffusions of liquid hydrogen and nitrogen. The governing equations for flow and heat transfer characteristics are expressed in terms of nonlinear coupled partial differential equations. The solutions of these equations are attempted numerically by employing the quasilinearization technique with the implicit finite difference approximation. It is found that EG is minimum for double diffusion(liquid hydrogen and heat diffusion)than triple diffusion(diffusion of liquid hydrogen, nitrogen and heat). The enhancing values of the radiation parameter R_(d) and temperature ratio θ_(w) augment the fluid temperature for steady and unsteady cases as well as the local Nusselt number. Because, the fluid absorbs the heat energy released due to radiation, and in turn releases the heat energy from the cylinder to the surrounding surface.展开更多
The post-hepatectomy recurrence rate of hepatocellular carcinoma(HCC)is persistently high,affecting the prognosis of patients.An effective therapeutic option is crucial for achieving long-term survival in patients wit...The post-hepatectomy recurrence rate of hepatocellular carcinoma(HCC)is persistently high,affecting the prognosis of patients.An effective therapeutic option is crucial for achieving long-term survival in patients with postoperative recurrences.Local ablative therapy has been established as a treatment option for resectable and unresectable HCCs,and it is also a feasible approach for recurrent HCC(RHCC)due to less trauma,shorter operation times,fewer complications,and faster recovery.This review focused on ablation techniques,description of potential candidates,and therapeutic and prognostic implications of ablation for guiding its application in treating intrahepatic RHCC.展开更多
The influence of pulse repetition frequency(PRF) on performance of wireless digital time hopping spread spectrum(THSS) ultrawide bandwidth(UWB) radio systems with PPM in dense multipath fading environments is firstly ...The influence of pulse repetition frequency(PRF) on performance of wireless digital time hopping spread spectrum(THSS) ultrawide bandwidth(UWB) radio systems with PPM in dense multipath fading environments is firstly investigated. The receiver used in this UWB system is a hybrid selection/maximal-ratio combining(H-S/MRC) diversity receiver in which L strongest multipath components out of N multipath diversity branches are selected and combined using maximal-ratio combining. The exact expressions for the bit error rate(BER) of this UWB system are firstly derived by using the virtual branch technique in term of PRF, the number of multipath components selected and combined L, and multipath spread of the channel and then this BER performance is evaluated. With the computer simulation for impulses having different pulse shapes, numerical results show that PRF, as well as pulse shape and the number of multipath diversity branches selected and combined L, has much effect on the BER performance of this UWB system in dense multipath fading environments. As PRF increases, the BER performance of this UWB system is much degraded under the conditions of fixed L and pulse shape.展开更多
Based on four intra-technique combined solutions in SINEX format, we tried at first to assess the accuracy of each single-technique Earth Orientation Parameters(EOPs) series over a past time interval of at least 15 ye...Based on four intra-technique combined solutions in SINEX format, we tried at first to assess the accuracy of each single-technique Earth Orientation Parameters(EOPs) series over a past time interval of at least 15 years by comparison with IERS EOP 08C04 combined solution as the reference in this paper. The EOPs studied here mainly consist of four elements, i.e. polar motion(XPO, YPO), Universal Time(UT1-UTC) and length-of-day(LOD). We combined these intra-technique EOP series, each of them associated with a given space geodetic technique by taking advantage of the relationship of the first three EOP components and three rotational parameters which carry the orientation of technique-related reference frame with respect to the estimated weekly inter-technique combined reference frame. Results indicated that the discrepancy between the pole coordinates(XPO, YPO) series, extracted from the intra-SLR combined loose-constraint solutions and the IERS EOP 08C04, seemed to be clearly characterized by systematic errors. Although both the XPO and YPO series determined by intra-VLBI combination had no significant characteristic of system error, they had relatively large difference values at some point with respect to the IERS EOP 08C04, which may be limited by the quantity of observation stations. Since the number of GPS stations is on the increase aimed at better global coverage, the accuracy of pole coordinates provided by IGS was superior to that derived from other space-geodetic techniques. As for DORIS XPO and YPO series from intra-DORIS combined minimal-constraint solutions, the discrepancy range of the former with respect to IERS EOP 08C04 was a little smaller than that of the latter. The objective of this study is twofold: on the one hand to analysis individual EOP series derived from the various space-geodetic techniques, on the other hand to present the new inter-technique combined EOP solution consistent with weekly inter-technique combined reference frame.展开更多
A series of nanosized Co/Zn/Mn/K composite catalysts for Fischer-Tropsch synthesis (FTS) were prepared by supercritical fluid drying (SCFD) method and common drying (CD) method. The nanosized cobalt-based cataly...A series of nanosized Co/Zn/Mn/K composite catalysts for Fischer-Tropsch synthesis (FTS) were prepared by supercritical fluid drying (SCFD) method and common drying (CD) method. The nanosized cobalt-based catalysts were characterized by XRD, TEM and BET techniques. Their catalytic performances were tested in a slurry-bed reactor under FTS reaction conditions. The drying and crystallization were carried out simultaneously during SCFD, therefore, the catalysts prepared by SCFD method have ideal structure and show the FTS performance superior to the others prepared by CD method. The FTS activity and selectivity were improved via adding Zn, Mn and K promoters, and less CH4 and CO2 as well as higher yield of C5+ products were achieved. The optimal performance of a 92% CO conversion and a 65% C5+ product yield was obtained over a catalyst with the component of Co/Zn/Mn/K = 100/50/10/7. Furthermore, the catalytic performance was studied under the conditions of liquid-phase and supercritical phase slurry-bed, and C5+ product yield were 57.4% and 65.4%, respectively. In summary, better catalytic performance was obtained using the nanosized catalyst prepared by SCFD method under supercritical reaction conditions, resulting in higher conversion of CO, less CO2 byproduct, and higher yield of C5+ products.展开更多
Abstract: Commercially available domperidone -a D2 receptor antagonist- is an immediate release formulation which has never been formulated into microspheres for sustained release. The present work aims towards study...Abstract: Commercially available domperidone -a D2 receptor antagonist- is an immediate release formulation which has never been formulated into microspheres for sustained release. The present work aims towards studying the effect of combination of a natural chitosan from an oyster shell of Mystilis edulis and HPMC (hydroxy propyl methyl cellulose) (spectracel 15 E) as polymer and tripolyphosphate as cross linking agent using wet gelation technique. The various polymer combination ratios for different batches were compared with a low molecular weight standard chitosan. The extracted chitosan - HPMC polymer combination ratios were chosen at ten levels: as batches B1, B2, B3, B4, B5, B6, B7, B8, B9, B10 for 1:1, 1:2, 2:1, 1:0, 0:1, 3:1, 1:3, 5:1, and 1:5 and 1:1 having 450:450, 300:600, 600:300, 900:0, 0:900, 675:225, 225:675, 750:150, 150:750, 450:450 mg respectively, while the quantity of domperidone and tripolyphosphate remained constant. B 11 and B 12 were formulated with standard chitosan and HPMC. The percentage yield of the formulated microspheres was determined and then evaluated for flowability, drug entrapment efficiency, drug release and mechanism of drug release by Fickian diffusion. The best batches of the domperidone loaded microspheres produced from the combination polymer were compared with the standard chitosan. The highest yields of microspheres were given by batches B12, B11, B10, and B4 with values of 50.1 ± 0.1%, 49.6 ± 0.1%, 46.6 :± 0.1%, and 46.1 ± 0.0% respectively while the lowest yield were 23.3 ± 0.2% and 23.6 ± 0.2%. B5 and B6 and B9 did not yield any microsphere. The bulk density, tapped density, compressibility and Hausner's ratio of the microspheres showed good flowability and high percent compressibility. The drug entrapment efficiency showed that the entrapment ranged from 54.2 to 97.2, where the least entrapment was B4 (54.2 ± 0.1) and the highest B12 (97.2 ± 0.2). The polymer surface of the microspheres as observed by SEM (scanning electron microscopy) was heterogeneous and porous which offers enhanced bioadhesivity. The dissolution study was used to determine the percentage drug release which ranged from 12.1% to 68.9% after 5 hours. Batches 1, 2, 3, 4, 7, and I 1 follow zero order kinetics via Fickian diffusion. The results indicate that microspberes of domperidone could be successfully formulated with a natural chitosan either alone or in combination with HPMC for sustained delivery of domperidone. Furthermore, the concentration of the natural polymer and HPMC employed in the formulation need to be carefully selected to enable the production of microspheres with the desired sustained release properties.展开更多
The synthetic path of a catalyst determines its morphology,species,and performance,and in-situ monitoring the catalyst formation process is fascinating and challenging.Herein,a newly developed synchrotron radiation sm...The synthetic path of a catalyst determines its morphology,species,and performance,and in-situ monitoring the catalyst formation process is fascinating and challenging.Herein,a newly developed synchrotron radiation smallangle X-ray scattering/X-ray diffraction/X-ray absorption fine structure(SAXS/XRD/XAFS)combined technique was used to in-situ monitor the isothermal-isobaric synthesis process of CO_(2)-assisted(BiO)_(2)CO_(3)(BOC)photocatalyst,and the atomic near-neighbor structure,crystalline structure and nanoscale particle size evolution with reaction time were simultaneously captured.The results show that both polyvinyl pyrrolidone and CO_(2)formed uniformly-distributed nano-sized scatterers in the Bi-based precursor solution,presenting short-range ordered structures to a certain extent.The as-prepared BOC catalytic particles underwent the evolution process of initial Bi(OH)3 precipitate,early-stage formed KBiO_(2)molecules,intermediate amorphous(BiO)4CO3(OH)2 nanoparticles,and finally crystallized flower-like BOC particles self-assembled by nanosheets.The flower-like BOC particles,Bi/BOC composite,and Bi nanospheres were further prepared with different synthesis paths.Flower-like BOC particles showed the best photocatalytic degradation performance of RhB.Scavenger experiment and theoretical calculation revealed the photocatalytic mechanisms of BOC.This work has implications for path-dependent synthesis of other catalysts.展开更多
posthuckling analysis is presented for the stilTened cylindrical shell of finite length subjected to combined loading of external liquid pressure and axial compression. The formulations are based on a boundary layer t...posthuckling analysis is presented for the stilTened cylindrical shell of finite length subjected to combined loading of external liquid pressure and axial compression. The formulations are based on a boundary layer theory of shell buckling, which includes the effects of nonlinear prebuckling deformations, nonlinear large deflections in the postbuckling range and initial geometrical imperfections of the shell. The 'smeared stifl'cner' approach is adopted for the stiffencrs. In the analysis a singular perturbation technique is used (o determine the interactive buckling loads and the postbuckling paths. Numerical examples cover the performance of perfect and imperfect, stringer and ring stiffened cylindrical shells. Typical results arc presented in the dimcnsionless graphical form.展开更多
Dent,a common mechanical damage on pipelines,is associated with a significant local plastic deformation.Dents can cause pipeline failures,especially when they are combined with other types of defects such as gouges,fa...Dent,a common mechanical damage on pipelines,is associated with a significant local plastic deformation.Dents can cause pipeline failures,especially when they are combined with other types of defects such as gouges,fatigue,corrosion,and cracks.In this work,a systematic review of various assessment methods and standards for pipeline dents,including the combination of a dent with other defects,is conducted.Generally,the methods available today are not sufficiently accurate and reliable to assess pipeline dents,especially the dent-defect combinations.For plain dents on pipelines,both the depthbased criterion and the strain-based criterion are commonly used in engineering.Their main problems include inaccuracy and conservatism.For a dent combined with other defects,the existing assessment techniques are not mature enough to give reliable results.Both experimental testing and numerical modeling through finite element(FE)analysis are capable of investigating the influence of dents and dent-defect combinations on burst failure pressure of the pipelines,although an approximation to the reality is still the main difficulty existing in the experimental testing and FE analysis.Nowadays,relevant studies on assessment techniques for plain dents,a dent with fatigue and a dent with a single gouge have been common in literature.The combinations of a dent with corrosion or cracks have been rarely assessed due to complicated mechanisms involving a multi-physics coupling effect.Development of novel assessment methods by integrating mechanical stress and strain,electrochemical reactions and steel metallurgy will be a key topic to accurately assess the dent-defect combinations for improved pipeline integrity.展开更多
In this paper, a Complex Wavelet Packet (CWP-MC-CDMA) system uplink model is proposed, based Multi-Carrier Code Division Multiple Access based on the analysis of the principle of MC-CDMA and the use of the optimized...In this paper, a Complex Wavelet Packet (CWP-MC-CDMA) system uplink model is proposed, based Multi-Carrier Code Division Multiple Access based on the analysis of the principle of MC-CDMA and the use of the optimized complex wavelet packet. Considering that the base station can adopt multiple re- ceiver antennas in the uplink, we employ the Space Diversity Combining (SDC) technique to improve the sys- tem pertbrmance via multiple antennas. The uplink performance of proposed CWP-MC-CDMA system with SDC technique is investigated over Rayleigh lading channel, and corresponding bit error rate analysis is given in detail. The system can avoid the decrease of spectrum efficiency of conventional MC-CDMA due to inserting cyclic prefix. Theoretical analysis and simulation result show that the application of SDC technique can improve the CWP-MC-CDMA system ability to combat spatial lading and various interferences effectively. Moreover, the proposed system based on SDC technique has superior Bit Error Rate (BER) performance over the Discrete Fourier Transform (DFT) and SDC based MC-CDMA system and the real wavelet packet and SDC based MC-CDMA system.展开更多
AIM: To investigate the combined antegraderetrograde endoscopic rendezvous technique for complete oesophageal obstruction and the swallowing outcome.METHODS: This single-centre case series includes consecutive patient...AIM: To investigate the combined antegraderetrograde endoscopic rendezvous technique for complete oesophageal obstruction and the swallowing outcome.METHODS: This single-centre case series includes consecutive patients who were unable to swallow due to complete oesophageal obstruction and underwent combined antegrade-retrograde endoscopic dilation(CARD) within the last 10 years. The patients' demographic characteristics, clinical parameters, endoscopic therapy, adverse events, and outcomes were obtained retrospectively. Technical success was defined as effective restoration of oesophageal patency. Swallowing success was defined as either percutaneous endoscopic gastrostomy(PEG)-tube independency and/or relevant improvement of oral food intake, as assessed by the functional oral intake scale(FOIS)(≥ level 3).RESULTS: The cohort consisted of six patients [five males; mean age 71 years(range, 54-74)]. All but one patient had undergone radiotherapy for head and neck or oesophageal cancer. Technical success was achieved in five out of six patients. After discharge, repeated dilations were performed in all five patients. During follow-up(median 27 mo, range, 2-115), three patients remained PEG-tube dependent. Three of four patients achieved relevant improvement of swallowing(two patients: FOIS 6, one patient: FOIS 7). One patient developed mediastinal emphysema following CARD, without a need for surgery.CONCLUSION: The CARD technique is safe and a viable alternative to high-risk blind antegrade dilation in patients with complete proximal oesophageal obstruction. Although only half of the patients remained PEG-tube independent, the majority improved their ability to swallow.展开更多
Coherent beam combination of two W-level fiber amplifiers with multi-dithering technique is demonstrated.In the experiment,the master laser is split into two channels.Multi-dithering technique is used for phase contro...Coherent beam combination of two W-level fiber amplifiers with multi-dithering technique is demonstrated.In the experiment,the master laser is split into two channels.Multi-dithering technique is used for phase control.One channel is modulated with a 100 kHz sine wave produced by signal generator,and DSP lock-in amplifier is used for electric signal processing in the feedback loop.When the phase control loop is off,the far field interference pattern is blurred and dynamic with 20% fringe contrast.When the f...展开更多
A postbuckling analysis is presented for a stiffened cylindrical shell of finite length subjected to combined loading of external pressure and a uniform temperature rise. The formulations are based on a boundary layer...A postbuckling analysis is presented for a stiffened cylindrical shell of finite length subjected to combined loading of external pressure and a uniform temperature rise. The formulations are based on a boundary layer theory of shell buckling, which includes the effects of nonlinear prebuckling deformations, nonlinear large deflections in the postbuckling range and initial geometrical imperfections of the shell. The 'smeared stiffener' approach is adopted for the stiffeners. The analysis uses a singular perturbation technique to determine the interactive buckling loads and the postbuckling equilibrium paths. Numerical examples cover the performances of perfect and imperfect, stringer and ring stiffened cylindrical shells. Typical results are presented in dimensionless graphical form.展开更多
Qinba Mountain Area is rich in plant resources. It is of great significance to study how to combine arbors,shrubs,and herbs in different regions and different climatic regions,reflect the beauty of color,form,and char...Qinba Mountain Area is rich in plant resources. It is of great significance to study how to combine arbors,shrubs,and herbs in different regions and different climatic regions,reflect the beauty of color,form,and charm. Besides,under different climatic and geomorphological conditions,adopting different land preparation methods and different cultivation techniques is helpful for increasing the survival rate and preservation rate,so as to provide certain technical basis for revitalizing development of rural areas and building the ecological barriers.展开更多
Great Animation not just drawing sequence of images or just combining images into frame by frame whatever motion will be, but Great Animation actually based on Physics, Biology and Lip sync. 2D Animation Hybrid Techni...Great Animation not just drawing sequence of images or just combining images into frame by frame whatever motion will be, but Great Animation actually based on Physics, Biology and Lip sync. 2D Animation Hybrid Technique is combination of Traditional Technique and Digital Technique, but the motion also based on analytical motion and physics. Traditional technique using mostly stop motion technique and experiment in any material animated objects, such as celluloid, sand, pebble, clay, doll, flour, or any objects that can be animated. This day digital technique is widely used mostly using computer hardware and software, and a lot of 2D animation software out there that can be used to create 2D animation. 2D Animation Hybrid Technique is a new technique that combining the traditional 2D animation technique but not using stop motion technique and with digital technique using computer and software, this technique become possible using image scanning technology that can digitizing any image from photo to hand drawn image. Then the sequence hand drawn animation edited in frame by frame also layer by layer using certain software in computer to create illusion of motion. The motion itself not just using any sense of art but also using physics, biology especially anatomy when needed to create such realism motion or perhaps funny motion in cartoon style animation.展开更多
SnO2/TiO2 nanocomposite photocata- lysts were prepared from TiCl4 and SnCl4·5H2O by supercritical fluid combination technique (SCFCT). This novel SCFCT is a combination of supercritical fluid drying method and so...SnO2/TiO2 nanocomposite photocata- lysts were prepared from TiCl4 and SnCl4·5H2O by supercritical fluid combination technique (SCFCT). This novel SCFCT is a combination of supercritical fluid drying method and sol-gel method. The XRD, TEM and FTIR results show that a new kind of active particle (Ti, Sn)O2 has formed and there is no sign of SnO2 crystals observed in the range of the doping concentration studied. The samples’ photocatalytic activity was evaluated by the degradation of acrylic acid. The results indicate that the SnO2/TiO2 nano- composite photocatalysts prepared through SCFCT show significant improvement in catalytic activity as compared to pure TiO2 or SnO2/TiO2 catalysts pre- pared by traditional drying (TD). The effect of H2O2 (0.167 v%) on the photodegradation was also inves- tigated. After the addition of H2O2, the chemical oxy- gen demand (COD) of acrylic acid, which had been treated with (15.1 mol%) SnO2/TiO2 nanocomposite photocatalysts for 3 h, was reduced from 400―500 to 20 mg/L.展开更多
文摘The Domain Decomposition Method(DDM) is a powerful approach to solving maily types of PDE's. DDM is especially suitable for massively Parallel computers. In the past, most research on DDM has focused on the domain splitting technique. In this paper. we focus our attention on use of a combination of techniques to solve each subproblem. The central question with DDM is that of how to doal with the pseodoboundary conditions. Here, we introduce a set of operators which act on the pseudo-boundaries in the solution process, referring to this new. procedure as the 'Generalized Domain Decomposition A.Jlethod(GDDM).' We have already obtained convergence factors for GDDM with certain classes of PDE's. These ctonvergence factors show that we can derive exact solutions of the whole problem for certain types of PDE's, and can get superior speed of convergence for other types.
文摘[Objectives]The extraction conditions of formula oolong tea were investigated by an orthogonal experiment.[Methods]The technical conditions were optimized by the 4C method,and the application of formula oolong tea extract in cigarettes was studied.[Results]①In the experimental range,the best sensory evaluation effect of formula oolong tea extract was obtained with extraction conditions of 70%ethanol as extraction solvent,extraction time h,extraction temperature 25℃,and ultrasonic frequency 80 kHz,and follow-up low-temperature concentration,low-temperature sedimentation and low-temperature centrifugation.②The effects of different centrifugal speeds on the quality of formula oolong tea extract were explored.The formula oolong tea extract obtained under the conditions of 3000 r/min and centrifugal time of 10 min showed the best evaluation effect with soft and delicate smoke,rich smoke fragrance,good comfort and refreshing mouthfeel.③The effective aroma components in the formula oolong tea extract were qualitatively analyzed by GC-MS.[Conclusions]This study provides high-quality raw materials and a theoretical basis for the research of independent flavor blending in cigarette industry enterprises.
基金the Foundation of the Science and Technology Committee of Hubei Province(2001ABA009)
文摘The thermal decomposition processes of ephedrini hydrochloridum and its kinetics are studied by TG-DTG techniques. A combined method, which includes Achar method, Coats-Redfera method, and Ozawa method, is put forward for determining kinetic model under non-isothermal conditions. By applying the combined method, it is determined that the thermal decomposition of ephedrini hydrochloridum is subjected to cylindrical symmetric diffusion. And the reaction function isƒ(α)=2(1-α)?, apparent activation energy (115.26±3.55) kJ·mol−1, pre-exponential factor 4.62×108 s−1. Results show that the combined method is feasible and simple.
文摘Diffusions of multiple components have numerous applications such as underground water flow, pollutant movement, stratospheric warming, and food processing. Particularly, liquid hydrogen is used in the cooling process of the aeroplane. Further, liquid nitrogen can find applications in cooling equipment or electronic devices, i.e., high temperature superconducting(HTS) cables. So, herein, we have analysed the entropy generation(EG), nonlinear thermal radiation and unsteady(time-dependent) nature of the flow on quadratic combined convective flow over a permeable slender cylinder with diffusions of liquid hydrogen and nitrogen. The governing equations for flow and heat transfer characteristics are expressed in terms of nonlinear coupled partial differential equations. The solutions of these equations are attempted numerically by employing the quasilinearization technique with the implicit finite difference approximation. It is found that EG is minimum for double diffusion(liquid hydrogen and heat diffusion)than triple diffusion(diffusion of liquid hydrogen, nitrogen and heat). The enhancing values of the radiation parameter R_(d) and temperature ratio θ_(w) augment the fluid temperature for steady and unsteady cases as well as the local Nusselt number. Because, the fluid absorbs the heat energy released due to radiation, and in turn releases the heat energy from the cylinder to the surrounding surface.
基金Supported by the National Key Research and Development Program of China,No.2020AAA0109503.
文摘The post-hepatectomy recurrence rate of hepatocellular carcinoma(HCC)is persistently high,affecting the prognosis of patients.An effective therapeutic option is crucial for achieving long-term survival in patients with postoperative recurrences.Local ablative therapy has been established as a treatment option for resectable and unresectable HCCs,and it is also a feasible approach for recurrent HCC(RHCC)due to less trauma,shorter operation times,fewer complications,and faster recovery.This review focused on ablation techniques,description of potential candidates,and therapeutic and prognostic implications of ablation for guiding its application in treating intrahepatic RHCC.
文摘The influence of pulse repetition frequency(PRF) on performance of wireless digital time hopping spread spectrum(THSS) ultrawide bandwidth(UWB) radio systems with PPM in dense multipath fading environments is firstly investigated. The receiver used in this UWB system is a hybrid selection/maximal-ratio combining(H-S/MRC) diversity receiver in which L strongest multipath components out of N multipath diversity branches are selected and combined using maximal-ratio combining. The exact expressions for the bit error rate(BER) of this UWB system are firstly derived by using the virtual branch technique in term of PRF, the number of multipath components selected and combined L, and multipath spread of the channel and then this BER performance is evaluated. With the computer simulation for impulses having different pulse shapes, numerical results show that PRF, as well as pulse shape and the number of multipath diversity branches selected and combined L, has much effect on the BER performance of this UWB system in dense multipath fading environments. As PRF increases, the BER performance of this UWB system is much degraded under the conditions of fixed L and pulse shape.
基金supported by the National Natural Science Foundation of China (grants 11773058)
文摘Based on four intra-technique combined solutions in SINEX format, we tried at first to assess the accuracy of each single-technique Earth Orientation Parameters(EOPs) series over a past time interval of at least 15 years by comparison with IERS EOP 08C04 combined solution as the reference in this paper. The EOPs studied here mainly consist of four elements, i.e. polar motion(XPO, YPO), Universal Time(UT1-UTC) and length-of-day(LOD). We combined these intra-technique EOP series, each of them associated with a given space geodetic technique by taking advantage of the relationship of the first three EOP components and three rotational parameters which carry the orientation of technique-related reference frame with respect to the estimated weekly inter-technique combined reference frame. Results indicated that the discrepancy between the pole coordinates(XPO, YPO) series, extracted from the intra-SLR combined loose-constraint solutions and the IERS EOP 08C04, seemed to be clearly characterized by systematic errors. Although both the XPO and YPO series determined by intra-VLBI combination had no significant characteristic of system error, they had relatively large difference values at some point with respect to the IERS EOP 08C04, which may be limited by the quantity of observation stations. Since the number of GPS stations is on the increase aimed at better global coverage, the accuracy of pole coordinates provided by IGS was superior to that derived from other space-geodetic techniques. As for DORIS XPO and YPO series from intra-DORIS combined minimal-constraint solutions, the discrepancy range of the former with respect to IERS EOP 08C04 was a little smaller than that of the latter. The objective of this study is twofold: on the one hand to analysis individual EOP series derived from the various space-geodetic techniques, on the other hand to present the new inter-technique combined EOP solution consistent with weekly inter-technique combined reference frame.
基金supported by Research Fund for the Doctoral Program of Higher Education (China,No.20050010014)
文摘A series of nanosized Co/Zn/Mn/K composite catalysts for Fischer-Tropsch synthesis (FTS) were prepared by supercritical fluid drying (SCFD) method and common drying (CD) method. The nanosized cobalt-based catalysts were characterized by XRD, TEM and BET techniques. Their catalytic performances were tested in a slurry-bed reactor under FTS reaction conditions. The drying and crystallization were carried out simultaneously during SCFD, therefore, the catalysts prepared by SCFD method have ideal structure and show the FTS performance superior to the others prepared by CD method. The FTS activity and selectivity were improved via adding Zn, Mn and K promoters, and less CH4 and CO2 as well as higher yield of C5+ products were achieved. The optimal performance of a 92% CO conversion and a 65% C5+ product yield was obtained over a catalyst with the component of Co/Zn/Mn/K = 100/50/10/7. Furthermore, the catalytic performance was studied under the conditions of liquid-phase and supercritical phase slurry-bed, and C5+ product yield were 57.4% and 65.4%, respectively. In summary, better catalytic performance was obtained using the nanosized catalyst prepared by SCFD method under supercritical reaction conditions, resulting in higher conversion of CO, less CO2 byproduct, and higher yield of C5+ products.
文摘Abstract: Commercially available domperidone -a D2 receptor antagonist- is an immediate release formulation which has never been formulated into microspheres for sustained release. The present work aims towards studying the effect of combination of a natural chitosan from an oyster shell of Mystilis edulis and HPMC (hydroxy propyl methyl cellulose) (spectracel 15 E) as polymer and tripolyphosphate as cross linking agent using wet gelation technique. The various polymer combination ratios for different batches were compared with a low molecular weight standard chitosan. The extracted chitosan - HPMC polymer combination ratios were chosen at ten levels: as batches B1, B2, B3, B4, B5, B6, B7, B8, B9, B10 for 1:1, 1:2, 2:1, 1:0, 0:1, 3:1, 1:3, 5:1, and 1:5 and 1:1 having 450:450, 300:600, 600:300, 900:0, 0:900, 675:225, 225:675, 750:150, 150:750, 450:450 mg respectively, while the quantity of domperidone and tripolyphosphate remained constant. B 11 and B 12 were formulated with standard chitosan and HPMC. The percentage yield of the formulated microspheres was determined and then evaluated for flowability, drug entrapment efficiency, drug release and mechanism of drug release by Fickian diffusion. The best batches of the domperidone loaded microspheres produced from the combination polymer were compared with the standard chitosan. The highest yields of microspheres were given by batches B12, B11, B10, and B4 with values of 50.1 ± 0.1%, 49.6 ± 0.1%, 46.6 :± 0.1%, and 46.1 ± 0.0% respectively while the lowest yield were 23.3 ± 0.2% and 23.6 ± 0.2%. B5 and B6 and B9 did not yield any microsphere. The bulk density, tapped density, compressibility and Hausner's ratio of the microspheres showed good flowability and high percent compressibility. The drug entrapment efficiency showed that the entrapment ranged from 54.2 to 97.2, where the least entrapment was B4 (54.2 ± 0.1) and the highest B12 (97.2 ± 0.2). The polymer surface of the microspheres as observed by SEM (scanning electron microscopy) was heterogeneous and porous which offers enhanced bioadhesivity. The dissolution study was used to determine the percentage drug release which ranged from 12.1% to 68.9% after 5 hours. Batches 1, 2, 3, 4, 7, and I 1 follow zero order kinetics via Fickian diffusion. The results indicate that microspberes of domperidone could be successfully formulated with a natural chitosan either alone or in combination with HPMC for sustained delivery of domperidone. Furthermore, the concentration of the natural polymer and HPMC employed in the formulation need to be carefully selected to enable the production of microspheres with the desired sustained release properties.
基金supported by the National Natural Science Foundation of China(12305372)the National Key R&D Program(2017YFA0403001 and 2022YFA1603802)of China。
文摘The synthetic path of a catalyst determines its morphology,species,and performance,and in-situ monitoring the catalyst formation process is fascinating and challenging.Herein,a newly developed synchrotron radiation smallangle X-ray scattering/X-ray diffraction/X-ray absorption fine structure(SAXS/XRD/XAFS)combined technique was used to in-situ monitor the isothermal-isobaric synthesis process of CO_(2)-assisted(BiO)_(2)CO_(3)(BOC)photocatalyst,and the atomic near-neighbor structure,crystalline structure and nanoscale particle size evolution with reaction time were simultaneously captured.The results show that both polyvinyl pyrrolidone and CO_(2)formed uniformly-distributed nano-sized scatterers in the Bi-based precursor solution,presenting short-range ordered structures to a certain extent.The as-prepared BOC catalytic particles underwent the evolution process of initial Bi(OH)3 precipitate,early-stage formed KBiO_(2)molecules,intermediate amorphous(BiO)4CO3(OH)2 nanoparticles,and finally crystallized flower-like BOC particles self-assembled by nanosheets.The flower-like BOC particles,Bi/BOC composite,and Bi nanospheres were further prepared with different synthesis paths.Flower-like BOC particles showed the best photocatalytic degradation performance of RhB.Scavenger experiment and theoretical calculation revealed the photocatalytic mechanisms of BOC.This work has implications for path-dependent synthesis of other catalysts.
文摘posthuckling analysis is presented for the stilTened cylindrical shell of finite length subjected to combined loading of external liquid pressure and axial compression. The formulations are based on a boundary layer theory of shell buckling, which includes the effects of nonlinear prebuckling deformations, nonlinear large deflections in the postbuckling range and initial geometrical imperfections of the shell. The 'smeared stifl'cner' approach is adopted for the stiffencrs. In the analysis a singular perturbation technique is used (o determine the interactive buckling loads and the postbuckling paths. Numerical examples cover the performance of perfect and imperfect, stringer and ring stiffened cylindrical shells. Typical results arc presented in the dimcnsionless graphical form.
基金supported by Natural Science and Engineering Research Council(NSERC),Canada
文摘Dent,a common mechanical damage on pipelines,is associated with a significant local plastic deformation.Dents can cause pipeline failures,especially when they are combined with other types of defects such as gouges,fatigue,corrosion,and cracks.In this work,a systematic review of various assessment methods and standards for pipeline dents,including the combination of a dent with other defects,is conducted.Generally,the methods available today are not sufficiently accurate and reliable to assess pipeline dents,especially the dent-defect combinations.For plain dents on pipelines,both the depthbased criterion and the strain-based criterion are commonly used in engineering.Their main problems include inaccuracy and conservatism.For a dent combined with other defects,the existing assessment techniques are not mature enough to give reliable results.Both experimental testing and numerical modeling through finite element(FE)analysis are capable of investigating the influence of dents and dent-defect combinations on burst failure pressure of the pipelines,although an approximation to the reality is still the main difficulty existing in the experimental testing and FE analysis.Nowadays,relevant studies on assessment techniques for plain dents,a dent with fatigue and a dent with a single gouge have been common in literature.The combinations of a dent with corrosion or cracks have been rarely assessed due to complicated mechanisms involving a multi-physics coupling effect.Development of novel assessment methods by integrating mechanical stress and strain,electrochemical reactions and steel metallurgy will be a key topic to accurately assess the dent-defect combinations for improved pipeline integrity.
基金Supported by China Postdoctoral Science Foundation, and Science Foundation of Jiangsu Province (BK2003089).
文摘In this paper, a Complex Wavelet Packet (CWP-MC-CDMA) system uplink model is proposed, based Multi-Carrier Code Division Multiple Access based on the analysis of the principle of MC-CDMA and the use of the optimized complex wavelet packet. Considering that the base station can adopt multiple re- ceiver antennas in the uplink, we employ the Space Diversity Combining (SDC) technique to improve the sys- tem pertbrmance via multiple antennas. The uplink performance of proposed CWP-MC-CDMA system with SDC technique is investigated over Rayleigh lading channel, and corresponding bit error rate analysis is given in detail. The system can avoid the decrease of spectrum efficiency of conventional MC-CDMA due to inserting cyclic prefix. Theoretical analysis and simulation result show that the application of SDC technique can improve the CWP-MC-CDMA system ability to combat spatial lading and various interferences effectively. Moreover, the proposed system based on SDC technique has superior Bit Error Rate (BER) performance over the Discrete Fourier Transform (DFT) and SDC based MC-CDMA system and the real wavelet packet and SDC based MC-CDMA system.
文摘AIM: To investigate the combined antegraderetrograde endoscopic rendezvous technique for complete oesophageal obstruction and the swallowing outcome.METHODS: This single-centre case series includes consecutive patients who were unable to swallow due to complete oesophageal obstruction and underwent combined antegrade-retrograde endoscopic dilation(CARD) within the last 10 years. The patients' demographic characteristics, clinical parameters, endoscopic therapy, adverse events, and outcomes were obtained retrospectively. Technical success was defined as effective restoration of oesophageal patency. Swallowing success was defined as either percutaneous endoscopic gastrostomy(PEG)-tube independency and/or relevant improvement of oral food intake, as assessed by the functional oral intake scale(FOIS)(≥ level 3).RESULTS: The cohort consisted of six patients [five males; mean age 71 years(range, 54-74)]. All but one patient had undergone radiotherapy for head and neck or oesophageal cancer. Technical success was achieved in five out of six patients. After discharge, repeated dilations were performed in all five patients. During follow-up(median 27 mo, range, 2-115), three patients remained PEG-tube dependent. Three of four patients achieved relevant improvement of swallowing(two patients: FOIS 6, one patient: FOIS 7). One patient developed mediastinal emphysema following CARD, without a need for surgery.CONCLUSION: The CARD technique is safe and a viable alternative to high-risk blind antegrade dilation in patients with complete proximal oesophageal obstruction. Although only half of the patients remained PEG-tube independent, the majority improved their ability to swallow.
文摘Coherent beam combination of two W-level fiber amplifiers with multi-dithering technique is demonstrated.In the experiment,the master laser is split into two channels.Multi-dithering technique is used for phase control.One channel is modulated with a 100 kHz sine wave produced by signal generator,and DSP lock-in amplifier is used for electric signal processing in the feedback loop.When the phase control loop is off,the far field interference pattern is blurred and dynamic with 20% fringe contrast.When the f...
文摘A postbuckling analysis is presented for a stiffened cylindrical shell of finite length subjected to combined loading of external pressure and a uniform temperature rise. The formulations are based on a boundary layer theory of shell buckling, which includes the effects of nonlinear prebuckling deformations, nonlinear large deflections in the postbuckling range and initial geometrical imperfections of the shell. The 'smeared stiffener' approach is adopted for the stiffeners. The analysis uses a singular perturbation technique to determine the interactive buckling loads and the postbuckling equilibrium paths. Numerical examples cover the performances of perfect and imperfect, stringer and ring stiffened cylindrical shells. Typical results are presented in dimensionless graphical form.
文摘Qinba Mountain Area is rich in plant resources. It is of great significance to study how to combine arbors,shrubs,and herbs in different regions and different climatic regions,reflect the beauty of color,form,and charm. Besides,under different climatic and geomorphological conditions,adopting different land preparation methods and different cultivation techniques is helpful for increasing the survival rate and preservation rate,so as to provide certain technical basis for revitalizing development of rural areas and building the ecological barriers.
文摘Great Animation not just drawing sequence of images or just combining images into frame by frame whatever motion will be, but Great Animation actually based on Physics, Biology and Lip sync. 2D Animation Hybrid Technique is combination of Traditional Technique and Digital Technique, but the motion also based on analytical motion and physics. Traditional technique using mostly stop motion technique and experiment in any material animated objects, such as celluloid, sand, pebble, clay, doll, flour, or any objects that can be animated. This day digital technique is widely used mostly using computer hardware and software, and a lot of 2D animation software out there that can be used to create 2D animation. 2D Animation Hybrid Technique is a new technique that combining the traditional 2D animation technique but not using stop motion technique and with digital technique using computer and software, this technique become possible using image scanning technology that can digitizing any image from photo to hand drawn image. Then the sequence hand drawn animation edited in frame by frame also layer by layer using certain software in computer to create illusion of motion. The motion itself not just using any sense of art but also using physics, biology especially anatomy when needed to create such realism motion or perhaps funny motion in cartoon style animation.
基金This work was supported by the National Natural Science Foundation of China (Grant No. 20076004) the Research Fund for the Doctoral Programof Higher Education (Grant No. 20050010014).
文摘SnO2/TiO2 nanocomposite photocata- lysts were prepared from TiCl4 and SnCl4·5H2O by supercritical fluid combination technique (SCFCT). This novel SCFCT is a combination of supercritical fluid drying method and sol-gel method. The XRD, TEM and FTIR results show that a new kind of active particle (Ti, Sn)O2 has formed and there is no sign of SnO2 crystals observed in the range of the doping concentration studied. The samples’ photocatalytic activity was evaluated by the degradation of acrylic acid. The results indicate that the SnO2/TiO2 nano- composite photocatalysts prepared through SCFCT show significant improvement in catalytic activity as compared to pure TiO2 or SnO2/TiO2 catalysts pre- pared by traditional drying (TD). The effect of H2O2 (0.167 v%) on the photodegradation was also inves- tigated. After the addition of H2O2, the chemical oxy- gen demand (COD) of acrylic acid, which had been treated with (15.1 mol%) SnO2/TiO2 nanocomposite photocatalysts for 3 h, was reduced from 400―500 to 20 mg/L.