Amount Of Injection Research Articles

Optimization of key parameters for continuous and precise nitrogen injection in goaf based on response surface methodology.

In order to solve the problems of coal spontaneous combustion, poor inerting effect of traditional nitrogen injection, and waste of resources in goaf, based on the response surface methodology and Box-Behnken combination test principle, the self-developed continuous and precise nitrogen injection and fire-fighting equipment was used to study the best possible combination of nitrogen injection position (20-90m), nitrogen injection amount (10-70 m3/min), and air supply volume (2100-2500 m3/min), aiming to minimize the width of the oxidation zone and CO concentration in goaf. The optimal key parameters of continuous precise nitrogen injection were determined as follows: nitrogen injection position 54.17m, nitrogen injection amount 31.04 m3/min, and air supply 2484.81 m3/min. Under this condition, the width of the oxidation zone was 29.21 ± 0.3m and the CO concentration was 28.1 ± 4.4ppm, which were similar to the predicted results of the model (the width of the oxidation zone was 29.41m; CO concentration was 27.28ppm). The reliability of the model was verified. These preliminary studies have achieved the purpose of rapid control of the fire in the whole region of the goaf and provided valuable lessons for similar nitrogen injection fire prevention and extinguishing technologies in goaf.

Gasoline compression ignition (GCI) combustion in a light-duty engine using double injection strategy

Controlling the oxides of nitrogen (NOx) and particulate matter (PM) emissions is one of the vital goals of compression ignition (CI) engines. Implementing stringent emissions regulations has motivated researchers to adopt various strategies for controlling emissions. Gasoline compression ignition (GCI) has emerged as a prime technology to control emissions and increase engine efficiency, while using low-octane gasoline as fuel in CI engines. Preheated air, hot exhaust gas recirculation (EGR), and negative valve overlap, are required to manage the combustion instabilities in the GCI engines. However these techniques have not been used in this study in order to reduce system complexity. Low octane test fuel was prepared (G80) by blending 80 % v/v gasoline and 20 % v/v diesel. This study involved experiments to evaluate the effects of main injection timing, split injection quantities (10–30 %), and engine load (brake mean effective pressure (BMEP): 3–5 bar) on a two-cylinder GCI engine’s performance, combustion, cyclic variability, emissions, and particulates. Conventional diesel combustion (CDC) mode experiments were performed using diesel. The results indicated a 5 % higher brake thermal efficiency (BTE) and comparable exhaust gas temperature (EGT) for the GCI mode compared to the baseline CDC mode. GCI combustion with low split ratio showed higher in-cylinder pressure than CDC mode. Baseline CDC mode showed < 3 % coefficient of variation of indicated mean effective pressure and peak pressure, whereas these parameters varied from 1 % to 9 % in the GCI mode. GCI mode engine exhibited ∼ 60 and 50 % lower NOx and PM emissions than baseline diesel mode engine. The double injection strategy improved GCI engine's performance and emission characteristics.

Study on influence factors of saline aquifer CO2 sequestration under the constraint of cap rock

In view of the practical problems faced by the CO2 sequestration in aquifers, this paper considers the influence of injection rate, water production rate, and other factors on CO2 injection amount, residual sequestration amount, dissolution sequestration amount, and pressure evolution under the constraint of cap rock breakthrough pressure is studied by using a numerical simulation method, and the sequestration potential is evaluated. The results show that: (1) Water production measures can improve CO2 injection, dissolution sequestration, and residual sequestration. (2) Low ratio of vertical permeability to horizontal permeability is conducive to the security and stability of CO2 sequestration in the long term. The research content provides support for the evaluation of CO2 saline aquifer sequestration potential and field practice.

SENSOR ELETROQUÍMICO PARA MONITORAMENTO DE SUOR

ABSTRACT Introduction: Attention is given to developing electrochemical sensors for the rapid and real-time measurement of lactate levels. The synthesis of electrochemical sensors is based on an electrode modified with a nanocomposite. Objective: Analyze an electrochemical sensor's feasibility for sports monitoring sweat in lactate. The Au@CNTs were the main focus of this study. Methods: The Au@CNTs composite was synthesized on the GCE surface and tested under pre-established protocols as a sensor. Results: The shape and structure of the modified electrodes were analyzed using SEM. The results showed that the Au@CNTs nanoparticles in the Au@CNTs nanocomposite were evenly distributed throughout the porous CNTs network. The performance of the developed sensor was measured using cyclic voltammetry and amperometry. The electrochemical biosensor responded linearly to lactate over phosphate buffer solution with a low detection limit and sensitivity. Conclusion: The experiment of this sensor evaluated lactate concentrations in real sweat samples that were exceptionally close to the injection amount, enabling it as an effective biosensor for the detection of lactate in sweat samples. Level of Evidence: Therapeutic Studies - Outcome Investigation.

Assessing a potential site for offshore CO2 storage in the Weixinan Sag in the northwestern Beibu Gulf Basin, northern South China Sea

AbstractGeologic carbon storage (GCS) activities, especially offshore, are still far insufficient worldwide. Sedimentary basins in the northern South China Sea (nSCS) are identified to be favorable to offshore GCS deployment. This study investigates by numerical reservoir simulations the performance of the Weixinan Sag in the northern depression of the Beibu Gulf Basin (BGB), which is considered the most promising area for CO2 offshore GCS in saline formations. Simulations of CO2 injection at a potential site with a normal fault indicate that the pressure buildup induced by CO2 horizontal injection could penetrate extremely low‐permeability faults or caprock formations. The CO2 plumes under higher injection pressures are more constrained in the horizontal direction and hence appear thicker while CO2 tends to spread out horizontally in conditions of low pressure. The impermeable fault renders the CO2 plume about 200 m smaller in size horizontally. Assuming the presence of a fault with a highly permeable core causes leakage to occur after about 30 years of injection, which accounts for only 0.04% the injected amount. For the vertical‐well injection case, the potential CO2 leakage only accounts for around 0.28% of the injection amount, which is far less than the criterion (i.e., 2%) required to make GCS worthwhile. The storage capacities of the formations are mainly controlled by the depths and thicknesses since both their porosities and permeabilities are comparable. The formation Jiaowei‐2 and Xiayang have the largest and second largest storage capacities, respectively, when using a fully perforated well for vertical injection. The average storage capacity of the studied site is 13.04 kg m−3, which is comparable to that of the formation Xiayang. Average injectivities of formations Jiaowei‐2, Xiayang, Weizhou‐1, and Weizhou‐3 are 8.29 × 10−5, 1.75 × 10−4, 6.58 × 10−5, and 2.99 × 10−3 kg s−1 Pa−1, respectively. © 2022 The Authors. Greenhouse Gases: Science and Technology published by Society of Chemical Industry and John Wiley &amp; Sons Ltd.

Plasma density transition-based electron injection in laser wake field acceleration driven by a flying focus laser

By using a high-intensity flying focus laser, the dephasingless [Phys. Rev. Lett. 124 134802 (2020)] or phase-locked [Nat. Photon. 14 475 (2020)] laser wakefield acceleration (LWFA) can be realized, which may overcome issues of laser diffraction, pump depletion, and electron dephasing which are always suffered in usual LWFA. The scheme thus has the potentiality to accelerate electrons to TeV energy in a single acceleration stage. However, the controlled electron injection has not been self-consistently included in such schemes. Only external injection was suggested in previous theoretical studies, which requires other accelerators and is relatively difficulty to operate. Here, we numerically study the actively controlled density transition injection in phase-locked LWFA to get appropriate density profiles for amount of electron injection. The study shows that compared with LWFA driven by lasers with fixed focus, a larger plasma density gradient is necessary. Electrons experience both transverse and longitudinal loss during acceleration due to the superluminal group velocity of the driver and the variation of the wakefield structure. Furthermore, the periodic deformation and fracture of the flying focus laser in the high-density plasma plateau make the final injected charge also depend on the beginning position of the density downramp. Our studies show a possible way for amount of electron injection in LWFA driven by flying focus lasers.

Multidimensional grid-based clustering with local differential privacy

Privacy-preserving clustering has received increasing research attention in recent years. Local differential privacy (LDP) is a privacy model without relying on trusted third parties. It plays a crucial role in distributed privacy-preserving clustering. Most previous methods focus on partition-based clustering (e.g., k-means), which necessitates many iterative interactions. Massive iterations cause a division of the privacy budget and increase the amount of individual noise, affecting the clustering utility. To address this issue, we turn to grid-based clustering and design the GC-LDP algorithm to balance the privacy and clustering utility with only three rounds of interactions. In GC-LDP, our core contribution is to develop a non-uniform grid division method via the coefficient of variation (CV), which can generate a grid structure approximating the global data distribution within two rounds of interactions. Besides, we designed a new perturbation mechanism to reduce the amount of individual noise injection. Further, a cell aggregation method is developed by exploring the relative density difference among grids to achieve multi-density clustering. Theoretical analysis and experiments on real-world datasets show that GC-LDP can obtain high-quality clustering results while satisfying local differential privacy.

Modeling and optimization of recovery enhancement efficiency by CO2/N2 mixture displacement in stimulated coal seams by destressing boreholes

Binary mixture (CO2/N2) displacement can effectively enhance coalbed methane recovery. A small gas injection amount in low-permeability coal seams leads to poor recovery enhancement efficiency (REE) by gas displacement. Constructing pressure-relief chambers inside the targeted coal seam can effectively improve the gas injection amount, yet the correlation between heterogeneous coal failure and the recovery enhancement by binary gas mixture remains unclear. Artificial parameters that influence recovery enhancement, including the diameter of pressure-relief chambers, drilling spacing, CO2 concentration, gas injection pressure and initial gas pressure, can be controlled or optimized in field practice. However, these parameters are not independent of but correlated with each other. This study aims to enhance gas recovery in deep mining coal seams. To this aim, a model of multi-component gas flow and geo-mechanics was established to model the gas displacement process in destressed coal seams. Next, advantages of the model considering coal failure and heterogeneity were revealed by comparing effective breakthrough radius and gas recovery amount, respectively. Subsequently, the evolution law of multi-physics was analyzed and the conclusions are as follows: (1) the model considering heterogeneous coal failure can well exhibit the storage and migration of multi-component gas; (2) the gas displacement influencing region can be divided into strong, weak and pianissimo displacement zones according to the regions that binary mixture acts on. Moreover, the pre-breakthrough REE and the post-breakthrough REE were proposed based on the characteristics of different gas injection stages. The respective and coupling effects of the artificial parameters on REE were further investigated by response surface methodology. The results reveal that the above five parameters (pressure-relief chamber diameter, drilling spacing, CO2 concentration, gas injection pressure and initial gas pressure) are dominant factors controlling the post-breakthrough REE, yet the latter three parameters have a notable impact on the pre-breakthrough REE. In addition, the pre-breakthrough REE and the post-breakthrough REE can hardly be improved at the same time and it is necessary to improve the REEs according to different gas injection stages. Finally, an injection-extraction alternating and multi-level optimization technology was proposed to further enhance gas displacement in low-permeability coal seams. The research results provide a theoretical reference for engineering practice.

Numerical simulation of co-combustion characteristics of semicoke and coke breeze in an ironmaking blast furnace

The co-combustion of semicoke and coal is recognized as a promising method for ironmaking blast furnace operation to reduce energy consumption and decrease the cost of hot metal. It is imperative to investigate the co-combustion behaviors and the in-furnace characteristics when injecting high ratio semicoke into blast furnace. Therefore, a three-dimensional model including tuyere and raceway for the injection of both semicoke and coke breeze with the actual operational parameters of a blast furnace was established. The model is then used to investigate the effects of oxygen enrichment ratio, injection amount and particle size on the combustion characteristics in the tuyere and raceway. Results showed that the high temperature zones expanded significantly with the increase of the oxygen enrichment ratio while they shrunk with the increase of the injection amount and the particle size. In order to obtain a higher burnout rate and a smooth operation of blast furnace, it is suggested that the oxygen enrichment ratio should be increased, the injection amount of semicoke and coal should not exceed 180 kg/t under the current working condition and the particle size of semicoke and coke breeze should be smaller than 60 µm.

Investigation of enhanced CO2 storage in deep saline aquifers by WAG and brine extraction in the Minnelusa sandstone, Wyoming

Geological CO2 sequestration in deep saline aquifers has been extendedly investigated to reach the goal of carbon neutral as large amount of CO2 can be reduced in a short time. This study investigates the feasibility of water-alternating-gas (WAG) injection and brine extraction on enhancing CO2 storage in a target deep saline aquifer, Minnelusa Sandstone in the Powder River Basin (PRB) of Wyoming. An integrated numerical model is developed to account for four scenarios: (1) CO2 continuous injection (CI) through one injection well, (2) WAG injection through one injection well, (3) CO2 CI through one injection well and brine extraction through one producer, (4) WAG injection through one injection well and brine extraction through one producer. Simulation results suggest that WAG injection and brine extraction corporately make it possible to enhance CO2 injectivity while securing CO2 storage safety. For instance, WAG injection considerably reduces structural trapping contribution while enhances dissolved and residual trapping contributions. As for brine extraction, it can decrease the maximum averaged reservoir pressure by 37% and 22% for CI and WAG injection, respectively. Besides, sensitive analyses of the operational parameters for the fourth scenarios are performed. Results reveal that, when the amount of total CO2 injection has been predetermined, CO2 injection time and rate within each period of WAG should be small whereas it is preferable to have large water injection time and rate. This is to secure desirable dissolved and residual trapping contributions (store CO2 with safety). Sensitive degree results confirm that CO2 injection rate, water injection time, and CO2 injection time of WAG injection exhibit significant effects on CO2 storage whereas the impacts of producer bottom-hole pressure (BHP), water injection rate, and CO2-water injection time are relatively weaker. This study not only sheds light on achieving double-win goal: enhance CO2 injectivity and store CO2 with safety, but also can be a critical reference for other CO2 storage in deep saline aquifers.

Effect of diesel/PODE/ethanol blends coupled pilot injection strategy on combustion and emissions of a heavy duty diesel engine

Ethanol has limited solubility in diesel. Polyoxymethylene dimethyl ethers (PODE) can enhance the miscibility of ethanol/diesel blends. The application of pilot injection strategy can improve combustion noise and NOx emissions. Thus, the effects of different diesel/PODE/ethanol blends coupled various pilot injection strategies on the combustion, performance and emissions were conducted in a six-cylinder heavy duty diesel engine. As renewable alternative fuel, PODE has the characteristics of high cetane number, high oxygen content and no CC bond, while ethanol has the characteristics of high volatility and high oxygen content. The results show that the significant differences in heat release rate (HRR) and maximum pressure rise rate (MPRR) among DP20, DPE5, DPE10 and DPE15 can be reduced by using the pilot injection, in that the differences in HRR timing and peak value of HRR are weakened. Both the brake and indicated thermal efficiency of blends can be improved by appropriately optimizing the pilot strategy, when compared with the case of single injection. The thermal efficiency of blends is more sensitive to the pilot injection quantity, while the CO and HC emissions are more sensitive to the pilot-main interval. For single injection, blending ethanol into PODE/diesel blends causes adverse effects of increasing hazardous gas emissions, while optimizing pilot injection strategy can reduce the hazardous gas emissions of the blends to the best level of diesel and significantly reduce soot emissions when compared to diesel.

Active Immunization Against NMDA NR1 Subunit as a Model of Autoimmune Encephalitis

Objective To identify and develop the optimal active immunization induction method for NMDAR encephalitis in rodents. Background Encephalitis is a devastating neurologic disorder with high morbidity and mortality. Many cases are autoimmune. N-Methyl-D-aspartic acid receptor (NMDAR) encephalitis (NMDARE), characterized by antibodies against the NMDAR in the blood and spinal fluid of patients, is the most common form of autoimmune encephalitis (AE). A translational rodent model of NMDARE would allow for in-depth studies into AE pathophysiology, leading to advances in the diagnosis and treatment of this debilitating neuropsychiatric disorder. Design/Methods 7-week-old female C57BL/6J mice were injected subcutaneously with an emulsion of complete Freund's adjuvant, attenuated Mycobacterium tuberculosis (TB), and a 30 amino acid peptide flanking the NMDAR NR1 subunit N368/G369 residue targeted by antibodies in NMDARE patients. Three different induction methods were tested by varying the amount and injection method of pertussis toxin, subcutaneous injection sites, reimmunization, and amounts of TB. Mice were bled biweekly and sacrificed at 2, 4, 6, 8, and 14 weeks. Serum and CSF NMDAR antibody titer; mouse behavior; hippocampal NMDAR protein and cluster density; and brain immune cell entry and cytokine content were examined. Results Immunized mice had serum and CSF NMDAR antibodies. Mice exhibited behavioral changes, altered hippocampal NMDAR protein, brain immune cell entry, and elevated cytokines in their brains. Titers were higher and changes were sustained in reimmunized mice. Conclusions Active immunization against the portion of the NMDAR targeted in patients with NMDARE resulted in robust production of NMDAR antibodies in the blood and spinal fluid, changes in hippocampal NMDAR protein, elevations in brain immune cells and cytokines, and behavioral changes in mice. Reimmunization was needed to sustain the responses. Active immunization therefore holds potential as a translational model of NMDARE, allowing for the creation of a novel generation of diagnostics and therapeutics.

Experimental study on influence of pressure fluctuation and cavitation characteristics of nozzle internal flow on near field spray

To investigate the causal relationship between the multi-frequency pressure fluctuations and the characteristics of the cavitation in the nozzle, as well as the influence mechanism on the near-field spray, a high-speed microscopic imaging technique was used to carry out the visualization experiment of the real-size tapered hole nozzle under different common rail pressures. The research show that the fluctuation trends such as pressure drop, fluctuation duration as well as coupling characteristics of high and low frequency can reflect the injection quantity, effective injection duration and cavitation morphology in the nozzle to some extent. The hydraulic servo action under different injection pressures affects the needle valve displacement, which in turn affects the throttling position and cavitation morphology during the injection process. After cavitation occurs, the pressure wave velocity and pressure wave transmission frequency in the pipe are obviously changed by affecting the bulk elastic modulus of the gas-mixed liquid. When geometry-induced cavitation occurs, the pressure fluctuates at low frequency, and the whole is relatively smooth. When string cavitation occurs, high-frequency pressure fluctuations tend to occur. The maximum lift and effective duration of needle valve determine the overall trend of pressure fluctuations, and cavitation characteristics affect the frequency characteristics and propagation speed of pressure fluctuations. The research provides theoretical support for the prediction method of fuel flow and cavitation characteristics in high-pressure nozzle based on high-low frequency identification of pressure fluctuations.

Effects of intra-operative fluid management under the guidance of stroke volume variability on short-term prognosis after thoracoscopic lobectomy.

We aimed to explore the influence of intra-operative fluid management under the guidance of stroke volume variability (SVV) on the short-term prognosis after thoracoscopic lobectomy. A total of 171 eligible patients from April 2017 to April 2019 were selected. All patients received intra-operative fluid management under the guidance of SVV, and were divided into low-, middle- and high-level groups (n = 57) using a random-numbers table. The general data, respiratory function indices at different time points, haemodynamic indices at different time points, use of vasoactive drugs, short-term prognosis indices and incidence of complications were compared. There were no significant differences in age, gender, operation time, one-lung ventilation time, amount of bleeding, arterial partial pressure of oxygen, arterial partial pressure of carbon dioxide, lung compliance and peak airway pressure at different time points, usage amount of anisodamine and incidence rate of complications among the three groups. In the low-level group, the fluid infusion amount and urine volume were significantly larger, the forced expiratory volume in one second (FEV1), percentage of FEV1 in the predicted value (FEV1%pred) and FEV1/forced vital capacity (FEV1/FVC) seven days after operation were higher, and the six-minute walk test (6MWT) distance was longer than those in the other two groups. The usage amount of dopamine, norepinephrine and esmolol was smaller, and the postoperative exhaust time was shorter than those in the other two groups. The low-level group had a smaller usage amount of isosorbide dinitrate injection and shorter length of postoperative hospital stay than the high-level group. Stroke volume had a significant difference at T2 and T3 in the low-level group, central venous pressure (CVP) and stroke volume had significant differences at T2 and T3 in the middle-level group, and heart rate (HR), mean arterial pressure and CVP were significantly different at T2 and T3 in the high-level group. Fluid management under the guidance of low-level SVV (8% ≤ SVV ≤ 9%) was conducive to the maintenance of stable haemodynamics in patients during thoracoscopic lobectomy, thereby improving short-term prognosis.

Water injection control modelling by using model-based calibration

&lt;p&gt;&lt;span lang="EN-US"&gt;This study presents the development of water injection system for turbocharged spark ignition engine. The water injection control system is built for turbocharged spark ignition (SI) engine where water was injected at the intake port just before the throttle body. The data was collected from the simulation through the GT-Power software to determine the optimized injection output for the engine. Single-stage statistical engine responses and boundary models were established by using Model-Based Calibration Toolbox. Control system was built using Simulink and simulation tests were conducted based on the speed and throttle position as the variables. The highest value of brake torque achieved in the GT-Power simulation was taken as the base value to determine the injection amount. The mean value of the predicted injection was recorded at 12.29 g/s while the variance of the predicted injection to the optimized injection was below 1%. The control system was simulated with the set predicted injection and the standard deviation of the predicted injection was 1.18. The control system simulation recorded a low percentage of 0.04% variance to the optimized injection with the pulse width modulation signal. The control system is ideal to be constructed and tested on actual engine test bed.&lt;/span&gt;&lt;/p&gt;

Optimal control design for drug delivery of immunotherapy in chemoimmunotherapy treatment

Background and ObjectiveThere are various approaches to control a mathematical dynamic of cancer, each of which is suitable for a special goal. Optimal control is considered as an applicable method to calculate the minimum necessary drug delivery in such systems. MethodsIn this paper, a mathematical dynamic of cancer is proposed considering tumor cells, natural killer cells, CD8+T cells, circulating lymphocytes, IL-2 cytokine and Regulatory T cells as the system states, and chemotherapy, IL-2 and activated CD8+T cells injection rate as the control signals. After verifying the proposed mathematical model, the importance of the drug delivery timing and the effect of cancer cells initial condition are discussed. Afterwards, an optimal control is designed by defining a proper cost function with the goal of minimizing the number of tumor cells, and two immunotherapy drug amounts during treatment ConclusionsResults show that inappropriate injection of immunotherapy time schedule and the number of initial conditions of cancer cells might result in chemoimmunotherapy failure and auxiliary treatment must be prescribed to decrease tumor size before any treatment takes place. The obtained optimal control signals show that with lower amount of drug delivery and a suitable drug injection time schedule, tumor cells can be eliminated while a fixed immunotherapy time schedule protocol fails with larger amount of drug injection. This conclusion can be utilized with the aim of personalizing drug delivery and designing more accurate clinical trials based on the improved model simulations in order to save cost and time.

Comparative evaluation of energy, performance, and emission characteristics in dual-fuel (CH4/Diesel) heavy-duty engine with RCCI combustion mode

This paper tries to approach the combustion phase of RCCI by changing the input parameters of the engine, a dual-fuel methane/natural gas engine, to compare the performance of the engine under the influence of modifications in these factors. The effect of the most important factors on the combustion of the RCCI engine including the start time of single-stage injection, two-stage injection schedule, compression ratio, the amount of injection with high reactivity and the angle of injection, numerically (CONVERGE-CFD) and Laboratory test are analyzed. The results show that CO, NOX and HC pollutants increase with a delay in the onset of single-stage injection. The results for different two-stage injection schedules show that by doubling the injection time of the second stage, the temperature inside the chamber and the rate of heat released decrease. But the data for changing the compression ratio from 11.5 to 19 indicate that the temperature of the mixture at the end of the compression phase has increased by more than 700 K, which will be directly related to the ignition start time and the combustion duration. In addition, increasing the compression ratio reduces the production of CO and HC pollutants. For smaller amounts of high reactive fuels, the maximum temperature moves to areas farther away from the top dead center, increasing CO and HC emissions. Also, using a larger injection angle (from 55° to 70°) will reduce CO, NOX and HC pollutants because more diesel fuel is trapped in the gaps and squish regions.

Comparison of different approaches of percutaneous vertebroplasty in the treatment of osteoporotic spinal compression fractures and analysis of influencing factors of re-fracture.

To compare the functional and radiological outcome of different approaches of percutaneous vertebroplasty (PVP) in the treatment of osteoporotic vertebral compression fractures (OVCF), and to analyze the factors affecting postoperative re-fracture in patients with OVCF. Medical data of 76 patients with OVCF who underwent PVP in our hospital from January 2021 to December 2021 were analyzed retrospectively. Based on the different intraoperative approaches, patients were divided into Unilateral-group (n=36) and Bilateral-group (n=40). The perioperative indexes, clinical efficacy, and spinal nerve function of the two groups were compared. Logistic regression analysis was used to determine the risk factors of postoperative re-fracture in patients with OVCF. The functional outcome was assessed with Oswestry disability index (ODI), American Spinal Injury Association (ASIA) nerve function classification and pain with Visual analogue scale (VAS). The radiological outcome was assessed by noting change of anterior vertebral height and change of kyphosis Cobb angle. The amount of intraoperative bleeding, the number of X-ray irradiation and the volume of injected bone cement in the Unilateral-group were lower, and the operation time was shorter than Bilateral-group (all P<0.05). One week after the operation, the anterior height of the vertebral body was higher, the Cobb angle of kyphosis was lower, the VAS score was higher, and the ASIA grade was lower in the Unilateral-group compared to the Bilateral-group (P<0.05). Logistic regression analysis showed that the age, bone mineral density, volume of bone cement injection and PD were risk factors of postoperative re-fracture in patients with OVCF. Unilateral PVP treatment of OVCF has the advantages of less intraoperative bleeding, less X-ray irradiation and shorter operation time. At the same time, bilateral PVP is associated with improved bone cement dispersion, and the effect of improving patients' pain is better than that in the Unilateral PVP. Postoperative risk of re-fracture in OVCF patients correlated with age, bone mineral density, amount of bone cement injection and pedicle diameter.

Lift-off region temperature field and planar flow field of a twin-nozzle reacting jet in hot crossflow

Secondary fuel injection affects the combustion organization and flame dynamic in axial fuel staging gas turbines. Here, we experimentally investigate a front-fuel rear-air twin-nozzle configuration in which the fuel and air can be independently injected to stabilize a lifted flame front, control the jet trajectory and tune the combustion mode in a very flexible way. A high repetition two-line formaldehyde planar laser induced fluorescence thermometry technique is used to measure the lift-off preheat zone temperature field of the flame with different amount of secondary air injection. The combustion flow field and the flame front dynamics are investigated using particle image velocimetry and CH* chemiluminescence. When the air to fuel ratio increases from 0 to 3, the preheat zone temperature, which is affected by the local equivalence ratio and injection air cooling, increases from 1300 K to 1600 K and then slightly declines. The lift-off region temperature and flow field dynamics are related to the variation of lift-off height, heat release rate and stability of the reacting jet in hot crossflow.

Laboratory Experimental Study on Polymer Flooding in High-Temperature and High-Salinity Heavy Oil Reservoir

Polyacrylamide (HPAM) and other traditional polymers have poor temperature resistance and salinity tolerance and do not meet the needs of high-temperature and high-salinity reservoirs. In this study, a new temperature-resistant and salinity-tolerant polymer QJ75-39 was synthesized using acrylamide (AM) as a hydrophilic monomer, 1-acrylamide-2-methylpropanesulfonic acid (AMPS) and N-vinylpyrrolidone (NVP) as functional monomers and DS-16 as a hydrophobic monomer. Through laboratory experiments, the properties (temperature resistance, salinity tolerance and aging stability), polymer injection and core displacement effect of the polymer were studied. The experimental results showed that the new polymer could meet the needs of polymer flooding technology in high-temperature and high-salinity reservoirs. Experiments showed that the polymer had a temperature resistance of 95 °C and a salinity tolerance of 1.66 × 105 mg/L. When the temperature was 95 °C and the TDS was 55,376.8 mg/L, the viscosity of the polymer was 31.3 mPa s, and the viscosity remained above 30 mPa·s after aging for 60 days. The polymer had good injectivity between 300 and 600 mD, and the injection pressure could reach equilibrium quickly. The oil recovery effectively increased with the grsowth in the amount of injected polymer. When the injection amount was 0.5 PV, the enhanced oil recovery was 20.65%. This study is of great significance for the application and popularization of polymer flooding technology in high-temperature and high-salinity reservoirs.