Experiment Research on Fine Regulation of Wheel Cylinder Pressure Using PWM Technology

A test bench of ABS/ASR integrated hydraulic system is developed by using pulse-width modulation （PWM） technology. The effective duty ratio range of ABS outlet valve has been tested in PWM control. With 50 Hz carrier wave frequency, the tests are performed to determine the correspondence between duty ratio and the wheel cylinder pressure variation. The duty ratio range of ABS outlet valve in PWM control is determined and an experimental model of pressure reduction velocity （PRV） of wheel cylinder using PWM control is established. By comparison and test of the experimental model and realization of controlling the duty ratio of ABS outlet valves, the fine regulation of wheel cylinder PRV is realized in the working of ABS/ASR braking regulation, which is important and valuable to the improvement of the ABS/ASR controlling effect.

Experimental study of the influencing factors and mechanisms of the pressure-reduction and augmented injection effect by nanoparticles in ultra-low permeability reservoirs

Nanoparticles(NPs)have gained significant attention as a functional material due to their ability to effectively enhance pressure reduction in injection processes in ultra-low permeability reservoirs.NPs are typically studied in controlled laboratory conditions,and their behavior in real-world,complex environments such as ultra-low permeability reservoirs,is not well understood due to the limited scope of their applications.This study investigates the efficacy and underlying mechanisms of NPs in decreasing injection pressure under various injection conditions(25—85℃,10—25 MPa).The results reveal that under optimal injection conditions,NPs effectively reduce injection pressure by a maximum of 22.77%in core experiment.The pressure reduction rate is found to be positively correlated with oil saturation and permeability,and negatively correlated with temperature and salinity.Furthermore,particle image velocimetry(PIV)experiments(25℃,atmospheric pressure)indicate that the pressure reduction is achieved by NPs through the reduction of wall shear resistance and wettability change.This work has important implications for the design of water injection strategies in ultra-low permeability reservoirs.

Non-alcoholic fatty liver disease,diabetes medications and blood pressure

New glucose-lowering agents reduce liver enzyme levels and blood pressure(BP).Whether this finding can be extended to non-alcoholic fatty liver disease(NAFLD)patients,in whom a bidirectional association of NAFLD measures and BP has been also demonstrated,remains by and large unknown.

In-situ synthesis of high thermal stability and salt resistance carbon dots for injection pressure reduction and enhanced oil recovery

Carbon dots(CDs)show great potential as a new type of oil-displacing agent for unconventional oil and gas development.However,the instability and easy aggregation epitomize the challenges that accompany the application of CDs in high temperature and high salinity(HT/HS)reservoirs.In this research,novel benzene sulfonate-modified carbon dots(BS-CDs)with remarkable thermal stability and salt resistance were fabricated through an in-situ electrochemical exfoliation method.Molecular simulation verifies that the introduction of benzene sulfonate groups substantially strengthens the electrostatic repulsion between BS-CDs,leading to outstanding dispersibility and stability even at a temperature of 100℃ and salinity of 14×10^(4) mg/L.Core flooding tests show that 0.05 wt.%BS-CDs nanofluid can significantly reduce the water injection pressure by 50.00%and enhanced oil recovery(EOR)to 68.39%under HT/HS conditions.According to the atomic force microscopy(AFM)scanning results,the adhesion force between the core(after BS-CDs treatment)and oil decreased by 11.94 times,indicating that the hydrophilicity of the core surface was increased.In addition,the distribution of the adhesion force curve is more concentrated,which means that the micro-scale wettability of the core changes from oil-wet to more homogeneous water-wet.This study provides a feasible way for the development and application of good thermal stability and salt resistance CDs in unconventional reservoir development.

Effects of pressure and plastic addition on sticking of fine iron ore particles in fluidized bed reduction

The adhesion of fine iron ore particles during fluidized bed reduction was studied using pressurized visible fluidized bed laboratory equipment.The results showed that the optimal operating parameters for pure hydrogen reduction under high pressure were reduction temperature of 1073 K,particle size of 0.18-0.66 mm,pure H_(2) linear velocity of 0.8 m/s,reduction pressure of 200 kPa,and reduction time of 50 min.When plastic particles were mixed into the fluidized bed,the optimal parameters were reduction temperature of 973 K,particle size of 0.18-0.66 mm,pure H_(2) linear velocity of 0.8 m/s,reduction pressure of 100 kPa,mass content of plastic particles of 8%,and reduction time of 65 min.The chemical reaction resistance is much higher than the inner diffusion resistance at the initial stage of the reaction,whereas,in later stage,the inner diffusion resistance exceeds the chemical reaction resistance.The contact area of iron atoms or iron whiskers gradually decreases with the increase in reduction pressure from 0.20 to 0.45 MPa,and the sticking trend gradually decreases.Adding plastic particles in the fluidized reduction process of fine iron ore can effectively inhibit the adhesion among fine iron ore particles.

Efficacy and safety of high-dose ultrasound cyclo-plasty procedure in refractory glaucoma

AIM:To evaluate the efficacy and safety of high-dose ultrasound cyclo-plasty(UCP)for the treatment of refractory glaucoma in Chinese patients.METHODS:In this 6-month retrospective study,37 eyes of 37 patients suffering from severe glaucoma with uncontrolled intraocular pressure(IOP)of≥21 mm Hg underwent 8-s ultrasonic cyclocoagulation with ten active piezoelectric elements.A complete ophthalmic examination was performed before and at 1 d,1,3,6 mo after UCP.Therapeutic success was defined as IOP reduction from baseline≥20%and IOP≥5 mm Hg without adding new glaucoma medication compare to baseline at the 6-month follow-up visit.In addition to mean IOP at each followup visit,medications used and complications were also detected and compared to baseline.RESULTS:After UCP procedure,the mean IOP was significantly reduced(P<0.01)from the preoperative 44.1±11.9 mm Hgto postoperative 26.7±11.8 mm Hg at 3 mo,and 30.4±14.5 mm Hg at 6 mo.The overall mean IOP reductions achieved at 3 and 6 mo were 39%and 31%compared to baseline IOP.Sixty-one percent of patients responded well to UCP treatment with a mean IOP reduction of 48%at 3 mo and 42%at 6 mo.Ocular pain in most of patients were alleviated.No serious intraoperative or postoperative complications occurred.CONCLUSION:High-dose UCP treatment is an effective and safe procedure to reduce IOP in Chinese patients with severe glaucoma.

The change of anterior segment parameters after cataract surgery in normal-tension glaucoma

AIM： To investigate the change of anterior chamber angle morphology and intraocular pressure （lOP） reduction after cataract surgery in patients with normal-tension glaucoma （NTG） using swept-source optical coherence tomography （SS-OCT）. METHODS： This prospective, comparative, observational study recruited patients into two groups. Group 1 was the control group including normal subjects except those with cataracts （cataract group, n=67 eyes of 67 patients）, and group 2 was NTG group including patients who were diagnosed with NTG and cataracts （n=43 eyes of 43 patients）, which were treated with phacoemulsification and intraocular lens implantation. Before surgery, and at postoperative 1 and 6too, anterior chamber angles were evaluated by SS-OCT under dark conditions using three- dimensional angle analysis scan protocol. Angle opening distance （AOD）, angle recess area （ARA）, and trabecular- iris surface area （TISA） at four quadrants （temporal, nasal, superior, and inferior） were calculated automatically by SS-OGT, after the observer marked scleral spurs. RESULTS： A total of 106 patients （54 males and 52 females） were enrolled in the study. Angle parameters, AOD, ARA, and TISA were increased after surgery in both groups. However, changes of angle parameters were only significant in group 2. In group 2, preoperative lOP was 13.2＋2.9 mm Hg, and postoperative lOP at 1 and 6mo were 10.5＋3.0 and 10.7＋2.8 mm Hg, respectively. In group 1, preoperative lOP was 12.42.8 mm Hg, and postoperative lOP at 1 and 6mo were 11.6＋2.5 and 12.0＋2.8 mm Hg, respectively. After cataract surgery, angle parameters changed significantly while IOP significantly reduced and was maintained in group 2 （P〈0.001）. The changes in angle parameters （＆AOD500, ATISAS00 at temporal; ＆AOD500, S, RA500 at nasal） were linearly correlated with postoperative IOP changes. CONCLUSION： Cataract surgery may have improved antedor chamber angle parameters and decreased lOP in NTG patients.

Natural Gas Pressure Reduction Station Self-powered by Fire Thermoelectric Generator

Pressure reduction station(PRS)is an essential facility in natural gas transmission,which owns the function of pressure reduction,demand-supply management and flow metering.However,a large number of PRSs are located in off-grid areas and powered by battery equipment resulting in high maintenance costs.So,how to realize the energy independence of these PRSs is an urgent issue to be solved.Therefore,the natural gas fired thermoelectric generation(FTEG)module,including gas flue,cover,TEGs and heat radiators,is designed for PRS in off-grid areas.Phase change material is introduced into the FTEG module to change the operation mode from continuous mode into a periodic mode,and the prototype of the FTEG module is built to discuss the generation performance in different modes.The results show that the generation efficiency of the FTEG module is improved by 63%in periodic mode compared with the continuous mode.Then,the numerical model is established to investigate the impacts of air coefficient,cold-side heat radiator and number of TEGs on the module performance.It found that the impacts of cold-side heat radiator and the number of TEGs are more significant than those of the air coefficient.After adjusting these key parameters,an optimized FTEG module with 32 TEGs is proposed,which has an average power generation of 16.4 W and a heat collection efficiency of 84.6%.Eventually,3 to 6 modules can be connected in series to meet the power requirement of 50 W to 100 W for PRS.This high-performance FTEG module can accelerate the process of achieving the energy independence of PRS and promote its application in mesoscale equipment.

Enthalpy and Exergy Transfers of High Pressure Switching Expansion Reduction

The energy balance,air internal energy,enthalpy and exergy transfers of high pressure switching expansion reduction(SER)are comparatively analyzed in this paper to give a better understanding about the exergy analysis and its difference between energy conversion analyses for the pneumatics.In SER,the exergy transfer effciency is much lower than the enthalpy effciency.The enthalpy effciency is primarily related to the initial pressure of supply tanks,and the exergy effciency is primarily related to the pressure reduction ratios.Heat transfers increase the internal energy,enthalpy and exergy of air;the influence on exergy is relatively small.The total enthalpy in SER decreases as the air temperature decreases in the expansion process of the air.And exergy loss is primarily related to the irreversible process of isenthalpic throttling but not energy conversion.Based on the analyses,to improve the exergy effciency of the pneumatics,the pressure reduction without power output should be avoided.

TRANSONIC WALL IN TERFERENCE CORRECTIONS FOR CIVIL AIRCRAFT MODEL TESTS

The correction method uses the static pressures measured near the tunnelwalls during model tests as boundary conditions. It is required that the flow near thewalls is subsonic and the freestream Mach number is less than 1. It is still valid whenthere are shock waves and supersonic pockets near the model as long as shock waves donot extend to walls, and the method is applicable to various ventilated wall or solid walltest sections. Corrections for three models tested abroad are in quite good agreementwith NASA's results, which are obtained by a nonhnear correction method. Thepresnet method has been apphed to B737 inodel tcsted in CARDC 1.2 m wind tunnel.The results show that this method is suitable for transonic wall interference correctionfor high aspect ratio airplane tests.

The association of cerebrospinal fluid pressure with optic nerve head and macular vessel density

The present study aims to investigate the effect of temporary cerebrospinal fluid pressure(CSFP) reduction on optic nerve head(ONH) and macular vessel density(VD) using optical coherence tomography angiography.Forty-four eyes of 44 adults with diagnostic lumbar puncture and CSFP reduction were recruited.Thirty-two eyes of 32 healthy volunteers were controls.ONH and macular VD images were evaluated differences between baseline and after CSFP reduction.The results showed that the mean CSFP decreased from(11.6±2.1) mm Hg to(8.2±3.4) mm Hg(P<0.001).VD in the macular regions decreased significantly after CSFP reduction in the study group(all P<0.05).The control group showed no significant changes in macular VD(all P>0.05).In the study group,decreased VD in the macular parainferior region was associated with CSFP reduction(R^(2)=0.192,P=0.003),the reduction of macular VD in parafoveal(R^(2)=0.098,P=0.018),parainferior(R^(2)=0.104,P=0.021),parasuperior(R^(2)=0.059,P=0.058),paranasal(R^(2)=0.057,P=0.042),paratemporal(R^(2)=0.079,P=0.026) was associated with mean ocular perfusion pressure decrease following CSFP reduction.ONH vessel density did not differ after CSFP reduction(all P>0.05).In conclusion,macular vessel density decreased in association with CSFP reduction.Retinal vessel density in the macular region is more sensitive than that in peripapillary region after CSFP reduction.