Effects of total pressures and equivalence ratios on kerosene/air rotating detonation engines using a paralleling CE/SE method

In this paper,the kerosene/air rotating detonation engines(RDE)are numerically investigated,and the emphasis is laid on the effects of total pressures and equivalence ratios on the operation characteristics of RDE including the initiation,instabilities,and propulsive performance.A hybrid MPI t OpenMP parallel computing model is applied and it is proved to be able to obtain a more effective parallel performance on high performance computing(HPC)systems.A series of cases with the total pressure of 1 MPa,1.5 MPa,2 MPa,and the equivalence ratio of 0.9,1,1.4 are simulated.On one hand,the total pressure shows a significant impact on the instabilities of rotating detonation waves.The instability phenomenon is observed in cases with low total pressure(1 MPa)and weakened with the increase of the total pressure.The total pressure has a small impact on the detonation wave velocity and the specific impulse.On the other hand,the equivalence ratio shows a negligible influence on the instabilities,while it affects the ignition process and accounts for the detonation velocity deficit.It is more difficult to initiate rotating detonation waves directly in the lean fuel operation condition.Little difference was observed in the thrust with different equivalence ratios of 0.9,1,and 1.4.The highest specific impulse was obtained in the lean fuel cases,which is around 2700 s.The findings could provide insights into the understanding of the operation characteristics of kerosene/air RDE.

Role of negative pressure wound therapy in total hip and knee arthroplasty

Negative-pressure wound therapy(NPWT) has been a successful modality of wound management which is in widespread use in several surgical fields. The main mechanisms of action thought to play a role in enhancing wound healing and preventing surgical site infection are macrodeformation and microdeformation of the wound bed, fluid removal, and stabilization of the wound environment. Due to the devastating consequences of infection in the setting of joint arthroplasty, there has been some interest in the use of NPWT following total hip arthroplasty and total knee arthroplasty. However, there is still a scarcity of data reporting on the use of NPWT within this field and most studies are limited by small sample sizes, high variability of clinical settings and end-points. There is little evidence to support the use of NPWT as an adjunctive treatment for surgical wound drainage, and for this reason surgical intervention should not be delayed when indicated. The prophylactic use of NPWT after arthroplasty in patients that are at high risk for postoperative wound drainage appears to have the strongest clinical evidence. Several clinical trialsincluding single-use NPWT devices for this purpose are currently in progress and this may soon be incorporated in clinical guidelines as a mean to prevent periprosthetic joint infections.

Low-pressure pneumoperitoneum with abdominal wall lift in laparoscopic total mesorectal excision for rectal cancer:initial experience

AIM To evaluate the safety and feasibility of a new technology combining low-pressure pneumoperitoneum(LPP) and abdominal wall lift(AWL) in laparoscopic total mesorectal excision(TME) for rectal cancer.METHODS From November 2015 to July 2017,26 patients underwent laparoscopic TME for rectal cancer using LPP(6-8 mm Hg) with subcutaneous AWL in Qilu Hospital of Shandong University,Jinan,China.Clinical data regarding patients' demographics,intraoperative monitoring indices,operation-related indices andpathological outcomes were prospectively collected.RESULTS Laparoscopic TME was performed in 26 cases(14 anterior resection and 12 abdominoperineal resection) successfully,without conversion to open or laparoscopic surgery with standard-pressure pneumoperitoneum.Intraoperative monitoring showed stable heart rate,blood pressure and paw airway pressure.The mean operative time was 194.29 ± 41.27 min(range:125-270 min) and 200.41 ± 20.56 min(range:170-230 min) for anterior resection and abdominoperineal resection,respectively.The mean number of lymph nodes harvested was 16.71 ± 5.06(range:7-27).There was no positive circumferential or distal resection margin.No local recurrence was observed during a median follow-up period of 11.96 ± 5.55 mo(range:5-23 mo).CONCLUSION LPP combined with AWL is safe and feasible for laparoscopic TME.The technique can provide satisfactory exposure of the operative field and stable operative monitoring indices.

A Combination of Varying Column Pressure and Total Reflux-Total Efflux in Batch Distillation Operation

A novel operation of batch distillation-combination of varyingcolumn pressure and total reflux-total efflux is studiedexperimentally. In the operation, the product is accumulated at thetop of the column under total reflux and then drained off completely,and the column pressure is varying in the whole process. This processhas been industrialized successfully with large profits. Theconventional model of batch distillation is improved by this methodeffectively: the separation efficiency and the yield of product areincreased greatly, the operation time is shortened and the productioncost is cut down. Moreover, the amount of condensation water isdecreased and the over-high reboiler temperature is lowered.

Total dose radiation effects of pressure sensors fabricated on Unibond-SOI materials

Piezoresistive pressure sensors with a twin-island structure were suc- cessfully fabricated using high quality Unibond-SOI (On Insulator) materials. Since the piezoresistors were structured by the single crystalline silicon overlayer of the SOI wafer and were totally isolated by the buried SiO2. the sensors are radiation-hard. The sensitivity and the linearity of the pressure sensors keep their original values after being irradiated by 60Co γ-rays up to 2.3×104Gy (H2O). However, the offset voltage of the sensor has a slight drift, increasing with the radiation dose. The absolute value of the offset voltage deviation depends on the pressure sensor itself. For comparison, corresponding polysilicon pressure sensors were fabricated using the similar process and irradiated at the same condition.

Changes of Amino Acid Content in Leaves of Agropyron cristatum Under Grazing Pressure

By measuring and comparing the contents of amino acids in Agropyron cristatum under grazing pressure, this study showed that the contents of total and each of the amino acids in A. cristatum changed little under grazing pressure. How- ever, the contents of free glycine （Gly） and proline （Pro） were very sensitive to grazing. Glycine content in grazing population was higher than that in non-grazing population at flowering stage; the content of free proline in non-grazing population was higher than that in grazing population at tillering, heading and especially flower- ing stage; the content of free proline under grazing pressure at maturity stage was higher than that of non-grazing population.

Extracting vanadium from stone-coal by oxygen pressure acid leaching and solvent extraction

Vanadium extraction from stone-coal was investigated by oxygen pressure acid leaching and solvent extraction.The mineralogy of the stone-coal from Tongren City of Guizhou Province,China,was investigated by various determination methods. The effects of leaching time,leaching temperature,leaching agent concentration,leaching L/S ratio,granularity of material,additive consumption were investigated based on the mineralogy.The results show that under the conditions of leaching time of 3-4 h, temperature of 150℃,sulfuric acid consumption of 25%?30%,ratio of liquid to solid of 1.2:1,the granularity less than 0.074 mm, additive consumption of 3%-5%,and oxygen pressure of 1.2 MPa,and the vanadium leaching rate can be more than 92%by the method of two-step pressurized acid leaching.The powdery V2O5 product with 99.52%in V2O5 content is obtained by the flowsheet of acid recovery,removing iron by reduction process,solvent extraction,precipitating vanadium with ammonium water,and pyrolysis from the stone-coal oxygen pressure acid-leaching solution.The total recovery efficiency of vanadium is above 85%,which is more than 20%higher than that obtained in the conventional process.Furthermore,the new process does not cause air pollution since no HCl or Cl2 is released by calcination of the raw material.

Modified Pressure Loss Model for T-junctions of Engine Exhaust Manifold

The T-junction model of engine exhaust manifolds significantly influences the simulation precision of the pressure wave and mass flow rate in the intake and exhaust manifolds of diesel engines. Current studies have focused on constant pressure models, constant static pressure models and pressure loss models. However, low model precision is a common disadvantage when simulating engine exhaust manifolds, particularly for turbocharged systems. To study the performance of junction flow, a cold wind tunnel experiment with high velocities at the junction of a diesel exhaust manifold is performed, and the variation in the pressure loss in the T-junction under different flow conditions is obtained. Despite the trend of the calculated total pressure loss coefficient, which is obtained by using the original pressure loss model and is the same as that obtained from the experimental results, large differences exist between the calculated and experimental values. Furthermore, the deviation becomes larger as the flow velocity increases. By improving the Vazsonyi formula considering the flow velocity and introducing the distribution function, a modified pressure loss model is established, which is suitable for a higher velocity range. Then, the new model is adopted to solve one-dimensional, unsteady flow in a D6114 turbocharged diesel engine. The calculated values are compared with the measured data, and the result shows that the simulation accuracy of the pressure wave before the turbine is improved by 4.3% with the modified pressure loss model because gas compressibility is considered when the flow velocities are high. The research results provide valuable information for further junction flow research, particularly the correction of the boundary condition in one-dimensional simulation models.

Atmospheric pressure gliding arc discharge plasma treatments for improving germination, growth and yield of wheat

Wheat （Triticum aestivum） seeds were treated with atmospheric pressure gliding arc discharge plasmas to investigate the effects on water absorption, seed germination rate, seedling growth and yield in wheat. The surface architectures and functionalities of the seeds were found to modify due to plasma treatments. 6 rain treatment was provided 95%-100% germination rate. For the treatment duration of 3 and 9 rain the growth activity, dry matter accumulation, leaves chlorophyll contents, longest spikes, number of spikes/spikelet and total soluble protein content in shoots were improved. The grain yield of wheat was increased ,--20% by 6 min treatment with H2O/O2 plasma with respect to control.

Total flavonoids of hawthorn leaves promote motor function recovery via inhibition of apoptosis after spinal cord injury

Flavonoids have been reported to have therapeutic potential for spinal cord injury.Hawthorn leaves have abundant content and species of total flavonoids,and studies of the effects of the total flavonoids of hawthorn leaves on spinal cord injury have not been published in or outside China.Therefore,Sprague-Dawley rats were used to establish a spinal cord injury model by Allen's method.Rats were intraperitoneally injected with 0.2 m L of different concentrations of total flavonoids of hawthorn leaves(5,10,and 20 mg/kg)after spinal cord injury.Injections were administered once every 6 hours,three times a day,for 14 days.After treatment with various concentrations of total flavonoids of hawthorn leaves,the Basso,Beattie,and Bresnahan scores and histological staining indicated decreases in the lesion cavity and number of apoptotic cells of the injured spinal cord tissue;the morphological arrangement of the myelin sheath and nerve cells tended to be regular;and the Nissl bodies in neurons increased.The Basso,Beattie,and Bresnahan scores of treated spinal cord injury rats were increased.Western blot assays showed that the expression levels of pro-apoptotic Bax and cleaved caspase-3 were decreased,but the expression level of the anti-apoptotic Bcl-2 protein was increased.The improvement of the above physiological indicators showed a dose-dependent relationship with the concentration of total flavonoids of hawthorn leaves.The above findings confirm that total flavonoids of hawthorn leaves can reduce apoptosis and exert neuroprotective effects to promote the recovery of the motor function of rats with spinal cord injury.This study was approved by the Ethics Committee of the Guangxi Medical University of China(approval No.201810042)in October 2018.

Thermodynamic analysis and combined cycle research on recoverable pressure energy in natural gas pipeline

Current research and ways of capturing mechanical energy are discussed in this paper. By the aid of the comprehensive thermodynamic analysis and Aspen simulation tool, the amount of a vailable work that can be produced from capturing the pressure energy has been calculated. Based on the comprehensive thermodynamic analysis, two systems have been proposed to capture pressure energy of natural gas to generate electricity. In this study, the expression of exergy is given which can be used in evaluating purposes. A problem with this multidisciplinary study is the complicated boundary condition. In conclusion, a technical prospect on recoverable natural gas pressure energy has been presented based on total energy system theory.

Oxygen pressure leaching-flotation joint process for Jinbaoshan platinum group minerals

An oxygen pressure leaching-flotation joint process was proposed to treat Jinbaoshan platinum group minerals to produce a desired concentrate. The result demonstrates that leaching parameters which include particle size, stirring speed, liquid-solid ratio, and the dosage of calcium lignosulfonate, simultaneously affect the leaching rates of base metals and the recovery of platinum group metals (PGMs). The complete dissolution of base metals sulfides leads to a reduction in the amount of flotation carrier for enriching PGMs, decreasing the recovery of PGMs. The optimum leaching conditions are determined as follows: liquid-solid ratio of 10 mL/g, 73% occupancy of ore particle size below 0.043 mm, stirring speed of 400 r/min, and 0.6 g dosage of calcium lignosulfonate. Under optimal conditions, the leaching rates of Cu, Ni and Fe are 87.6%, 87.6% and 90.3%, respectively. The grade of PGMs enriched in the flotation concentrate is 420 g/t through the flotation technology.

Study on Reducing Injection Pressure of Low Permeability Reservoirs Characterized by High Temperature and High Salinity

In view of the problems of high injection pressure and low water injection rate in water injection wells of low permeability reservoirs featuring high temperature and high salinity,two new surfactants were synthesized,including a quaternary ammonium surfactant and a betaine amphoteric surfactant.The composite surfactant system BYJ-1 was formed by mixing two kinds of surfactants.The minimum interfacial tension between BYJ-1 solution and the crude oil could reach 1.4×10^(-3) mN/m.The temperature resistance was up to 140℃,and the salt resistance could reach up to 120 g/L.For the low permeability core fully saturated with water phase,BYJ-1 could obviously reduce the starting pressure gradient of low permeability core.While for the core with residual oil,BYJ-1 could obviously reduce the injection pressure and improve the oil recovery.Moreover,the field test showed that BYJ-1 could effectively reduce the injection pressure of the water injection well,increase the injection volume,and increase the liquid production and oil production of the corresponding production well.

Temperature Compensation Algorithm for Hydraulic System Pressure Control

In this paper the control mechanism of solenoid valve is analyzed,which shows the solenoid valve control is actually the control of coil current.The response characteristic of coil current is related to coil inductance and resistance.The coil resistance is influenced greatly by the ambient temperature and the self-heating of coil,which affects the control precision of coil current.First,considering the heat dissipation mode of coil,the coil temperature model is established from the perspective of heat conduction,and a temperature compensation algorithm for hydraulic system pressure control is put forward.Then the hardware-in-the-loop testbed is set up by using the dSPACE platform,carrying out wheel cylinder pressurization tests with inlet valve fully opened at-40℃ and 20℃,and testing the actual pressure of wheel cylinder with the target pressures at-40℃ and 6 000 kPa/s(pressurization rate).The results show that the pressure control temperature compensation algorithm proposed in this paper accurately corrects the influence of resistance temperature drift on the response accuracy of wheel cylinder pressure.After the correction,the pressure difference is less than 500 kPa,which can meet the control accuracy requirements of solenoid valve,enriching the linear control characteristic of solenoid valve.

Effects of Gamma-Ray Irradiation on Dielectric Surface Breakdown of Polybutylene Naphthalate and Polybutylene Terephthalate Under Reduced Pressure

With the increasing application of electric and electronic devices in space and nuclear power stations, the polymeric insulation materials are inevitably exposed to various kinds of environments. Accordingly, it becomes necessary to investigate the effects of the radiation and air pressure on insulation materials. This paper describes the effects of gamma-ray irradiation and reduced pressure on dielectric breakdown of polybutylene naphthalate (PBN) and polybutylene terephthalate (PBT) by applying a DC pulse voltage. Both PBN and PBT were irradiated in air up to 100 kGy and then up to 1 000 kGy with a dose rate of 10 kGy/h by using a60Co gamma-source. The effects of total dose and reduced pressure on the time to dielectric breakdown and discharge quantity were discussed. Obtained results show that, while increasing the total dose, the discharge quantity decreased with PBN, but increased with PBT. With decreasing the air pressure, the discharge quantity increased with PBN, but decreased with PBT. With increasing the total dose, the time to dielectric breakdown increased with PBN, but decreased with PBT. With decreasing the air pressure, the time to dielectric breakdown increased with both PBN and PBT. The experimental results suggest that the chemical structure of polybutylene polymers plays a main role in the result of radiation reaction, which is related to cross-linking and degradation reaction.

Effects of Pressure on Bubble Size and Separation of BSA by a Semi-batch Foaming Process

Experiments were conducted to obtain the values of the Sauter bubble size, enrichment and recovery of bovine serum albumin （BSA） in a semi-batch col- umn fitted with a stainless steel sparger at elevated pressure. The effects of Sur- face tension, surfactant concentration, foam/solution height ratio and air flow rate on the separation performance were investigated, and the results showed that good en- richments and recoveries can be achieved for bovine serum albumin operated at el- evated pressures. Especially the size of bubbles generated by the stainless steel sparger was smaller at higher pressures which is favorable to the foam separation process. Furthermore, the separation mechanism of bovine serum albumin operated at elevated pressure was also discussed.

Enhanced recovery after surgery pathway: The use of fascia iliaca blocks causes delayed ambulation after total hip arthroplasty

BACKGROUND Fascia iliaca compartment blocks(FIBs) have been used to provide postoperative analgesia after total hip arthroplasty(THA). However, evidence of their efficacy remains limited. While pain control appears to be satisfactory, quadriceps weakness may be an untoward consequence of the block. Prior studies have shown femoral nerve blocks and fascia iliaca blocks as being superior for pain control and ambulation following THA when compared to standard therapy of parenteral pain control. However, most studies allowed patients to ambulate on post-operative day(POD) 2-3, whereas new guidelines suggest ambulation on POD 0 is beneficial.AIM To determine the effect of FIB after THA in patients participating in an enhanced recovery after surgery(ERAS) program.METHODS We conducted a retrospective analysis of patients undergoing THA with or without FICBs and their ability to ambulate on POD 0 in accordance with ERAS protocol. Perioperative data was collected on 39 patients who underwent THA.Demographic data, anesthesia data, and ambulatory outcomes were compared.RESULTS Twenty patients had FIBs placed at the conclusion of the procedure, while 19 did not receive a block. Of the 20 patients with FIB, only 1 patient was able to ambulate. Of the 19 patients without FIB blocks, 17 were able to ambulate. All patients worked with physical therapy 2 h after arriving in the post-anesthesia care unit on POD 0.CONCLUSION Our data suggests an association between FIB and delayed ambulation in the immediate post-operative period.

An improved correlation to determine minimum miscibility pressure of CO2–oil system

An accurate and reliable estimation of minimum miscibility pressure(MMP) of CO2-oil system is a critical task for the design and implementation of CO2 miscible displacement process.In this study,an improved CO2-oil MMP correlation was developed to predict the MMP values for both pure and impure CO2 injection cases based on ten influential factors,i.e.reservoir temperature(TR),molecular weight of C7+oil components(MWC7+),mole fraction of volatile oil components(xvol),mole fraction of C2-C4 oil components(xC2-C4),mole fraction of C5-C6 oil components(xCs-5-C6),and the gas stream mole fractions of CO2(yCO2),H2S(yH2S),C1(yC1),hydrocarbons(yHC)and N2(yN2).The accuracy of the improved correlation was evaluated against experimental data reported in literature concurrently with those estimated by several renowned correlations.It was found that the improved correlation provided higher prediction accuracy and consistency with literature experimental data than other literature correlations.In addition,the predictive capability of the improved correlation was further validated by predicting an experimentally measured CO2-Oil MMP data,and it showed an accurate result with the absolute deviation of 4.15%.Besides,the differential analysis of the improved correlation was analyzed to estimate the impact of parameters uncertainty in the original MMP data on the calculated results.Also,sensitivity analysis was performed to analyze the influence of each parameter on MMP qualitatively and quantitatively.The results revealed that the increase of xC2-C4,xC5-C6 and yH2 S lead to the decrease of MMP,while the increase of TR,MWC7+,xvol,yCO2,YC1,yHC and yN2 tend to increase the MMP.Overall,the relevance of each parameter with MMP follows the order of TR> xC5-C6> MWC7+> xvol> yH2 S> yHC> yCO2>yC1>yN2>xC2-C4.

Modular zonal fluid sampling and pressure testing technology for production well

To accurately obtain development dynamic data such as zonal pressure and fluid parameters of each oil layer in the late development stage of a high water-cut old oilfield, a modular zonal sampling and testing technology with the characteristics of modularization, full electronic control and rapidity was proposed and developed. Lab testing and on-site testing was carried out. The modular zonal sampling and testing system is composed of 10 functional modules, namely ground control system, downhole power supply module, drainage pump, electronically controlled anchor, electronically controlled packer, electronically controlled sampler, magnetic positioning sub, terminal sub, adapter cable, and quick connector. Indoor tests have confirmed that the performance parameters of each module meet the design requirements. The downhole function modules of the system can withstand pressures up to 35 MPa and temperatures up to 85 ℃. The rubber cylinder of the electronically controlled packer can withstand a pressure difference of more than 10 MPa. The electronically controlled anchor has an anchoring force of greater than 6.9 t, and can be forcibly detached in the event of an accident. The discharge pump has a displacement of 0.8 m;/d and a head of 500 m. The electronically controlled sampler can meet the requirement of taking 500 mL of sample in each of the 3 chambers. Field tests in Jilin Oilfield show that the system can realize rapid isolation and self-check of isolation of a certain production interval downhole, as well as layer-by layer pressure build-up test. The drainage pump can be used to discharge the mixed liquid between the upper and lower packers and near the wellbore to obtain real fluid samples of the tested formation interval. The data obtained give us better understanding on the pay zones in old oilfields, and provide important basis for development plan adjustment, reservoir stimulation, and EOR measures.

Unlocking the potentials of gel conformance for water shutoff in fractured reservoirs: Favorable attributes of the double network gel for enhancing oil recovery

The double-network prepared with an in-situ monomer gel and a fast-crosslinked Cr(III) gel is introduced to develop a thixotropic and high-strength gel (THSG), which is found to have many advantages over the traditional gels. The THSG gel demonstrates remarkable thermal stability, and no syneresis is observed after 12 months with high salinity brine (95,500 mg/L). Moreover, the SEM and XRD results indicate that the gel is intercalated into the lamellar structures of Na-MMT, where the gel can form a uniform and compact structure. In addition, the THSG gel has an excellent swelling behavior, even in the high salinity brine. In the slim tube experiments, the THSG gel exhibits high rupture pressure and improves blocking capacity after being ruptured. The core flooding results show that a layer of gel filter cake is formed on the face of the fracture, which may be promoted by a high matrix permeability, a small aperture fracture, and a high injection rate. After the gel treatment, the fracture can be completely blocked by the THSG gel. It is found that a high incremental oil recovery (65.3%) can be achieved when the fracture was completely blocked, compared to 40.2% if the gel is ruptured. Although the swelling of ruptured gel can improve oil recovery, part of the injected brine may be channeled through the gel-filled fractures, resulting in a decrease in the sweep efficiency. Therefore, the improved blocking ability by gel swelling (e.g., in fresh water) may be less efficient to contribute to an enhancement of oil recovery. It is also found that the pressure gradient and residual resistance factor to water (Frrw) are higher if the matrix is less permeable, indicating that the fractured reservoir with lower matrix permeability may require a higher gel strength for treatment. The findings of this study may provide novel insights on designing robust double network gels for water shutoff in fractured reservoirs.