Valve Opening Time Research Articles

Density-profile imaging using a second harmonic dispersion interferometer configured with reflective-beam expanders.

A Second-Harmonic Dispersion Interferometer (SHDI) is assembled to measure the two-dimensional, line-integrated density profile of a pulsed-plasma jet using probe-beam diameters well beyond the 1mm diameters typically used in such instruments. An initial prototype demonstrated the technique using 7mm beam diameters, which are now increased to 35mm diameter using two types of beam expanders: an achromatic-beam expander (ABE) or a reflective-beam expander (RBE). ABEs were found to add a periodic background to the measured-phase image with a magnitude of the order of Δϕ ∼ 2π radians, compared to the background phase noise level in the system configured without beam expanders at Δϕbg ∼ 0.025 radians. Subtraction of the background phase in a sample image reduced the effect of the ABE phase offset to a level of Δϕ ∼ 0.1 radians, enhancing the quality of the density measurements. Reflective-beam expanders (RBEs) did not modify the background phase appreciably and were a significant improvement, allowing the instrument to be used for 2D (r, z) density-profile measurements of a 3cm diameter × 5cm long, pulsed-plasma jet. Variations in the timing parameters for the plasma gun, specifically the gas valve opening time and the gas-injection delay, for a constant discharge current were used to map the plasma gun's performance, indicating a nominal line-integrated electron density of Nedl ≳ 3 × 1015 cm-2 and a volumetric density of Ne ≃ 9 × 1015cm-3. The results obtained for the RBE configuration demonstrate that the 2D-SHDI platform may be scaled to even larger sample areas and a rep-rated system, with the ability to potentially provide for a reproducible, time-resolved (∼1 ns), high resolution (∼100μm) measurement of 2D plasma-density profiles.

Effects of continuous variable valve timing and duration on fuel/air mixture formation

With increasing global regulations on particulate emissions, the particulate matter and number released under cold start and high-load conditions have become crucial. Under such conditions, the particulate emissions from port fuel injection engines can be significant and comparable to those from gasoline direct injection engines. In this case, fuel evaporation and mixture formation contribute to the reduction in particulate emissions. One method to improve these characteristics is to enhance the in-cylinder flow and turbulence kinetic energy. Therefore, in this study, we investigated the effect of in-cylinder flow enhancement on the particulate emissions reduction in port fuel injection engines. Simulations were conducted with various intake valve timings and durations under cold-start conditions. We then performed engine experiments to confirm the reduction in particulate number. The results showed that the relationship between the intake valve open timing and piston speed was crucial. Opening the intake valve to its maximum value slightly after the point of peak piston velocity resulted in a higher flow intensity and turbulence kinetic energy during the compression stroke. In addition, the experimental results indicated that improving the in-cylinder flow using continuous variable valve timing reduced the particulate number by 27.51 %.

FEA-Based Camshaft Design and Analysis on a Range of Heat-Treated Materials

Camshafts play a critical role in internal combustion engines, dictating the timing and duration of valve opening and closing events. To ensure optimal engine performance and longevity, camshaft design must balance factors such as strength, durability, and weight. Finite Element Analysis (FEA) offers a powerful tool for evaluating camshaft designs under varying operating conditions. This paper presents a comprehensive study on the design and analysis of camshafts using FEA, focusing on the influence of different heat-treated materials. The study begins with an overview of material selection criteria for camshaft applications, considering factors such as strength, fatigue resistance, and wear characteristics. Various materials high-performance alloys are investigated for their suitability and performance enhancements through heat treatment processes such as carburizing, quenching, and tempering. A detailed 3D CAD model of the camshaft geometry is developed, capturing key features such as lobes, journals, and bearings. Finite element meshing techniques are employed to ensure accurate representation of the geometry and precise stress analysis. Boundary conditions are defined to simulate realistic operating conditions, including forces exerted by cam followers and valve springs. Material properties are assigned to finite elements based on the selected materials and heat treatment parameters. Static and dynamic FEA analyses are conducted to evaluate stress distribution, deformation, fatigue life, and natural frequencies of the camshaft under varying load scenarios. The results of the FEA analyses are used to optimize the camshaft design iteratively, considering factors such as weight reduction, performance enhancement, and durability improvement. Validation of FEA results is performed through physical testing and comparison with empirical data. Overall, this paper provides valuable insights into the design and analysis of camshafts using FEA, highlighting the importance of material selection and heat treatment processes in optimizing camshaft performance and reliability in automotive engine applications. Key Words: Design, Analysis, geartrain, idler gear, FEA, reciprocating motion, Solid works, CAD, ANSYS, efficiency, IC engines, camshaft.

Analysis of dual biodiesel doped with different proportions of TiO2 nanoparticles

India is home of two species Madhuca indica and jatropha. Mahua, also referred to as Illupai maram in Tamil and Hippi in Kannada, is a plant that grows well in arid, barren areas. The seeds from the tree dubbed the “Indian butter tree.” With a compression ratio of 17.5:1, an inlet valve opening timing of 13O bTDC, and an injection pressure of 200 bars, a performance and emission analysis for various proportions of nano additives with biodiesel blend was conducted at various loads ranging from zero load to 100 % of brake power. Using a brake drum dynamometer, load was applied to the engine. It is noted how long it takes to use 10 ml of gasoline for each load. The diesel engine employed is a single-cylinder, direct-injection Kirloskar engine with typical inlet valve timing, compression ratio, and injection pressure, 1500 rpm is the continuous speed. The components of exhaust gases change depending on the load. Standard diesel is used to run the engine at first to gather baseline data, and then JME5MME15 blends with different amounts of nano additives added for the experiment. These amounts are 25 PPM, 50 PPM, and 75 PPM. The reading is taken using the same process. Among the various blends analyzed JME5MME15 has an SFC of 0.321 kg/kW h. The SFC results for JME5MME15T25 are 0.382 kg/kWh. JME5MME15T50 and JME5MME15T75 have similar values of 0.282 kg/kWh and 0.421 kg/kWh. The SFC of the JME5MME15T50 is almost identical to that of diesel.

Towards automatic detection and classification of swimming pectinids behaviour: first developments on great scallops (Pecten maximus)

ABSTRACT Over the past decades, valvometric techniques have been commonly used to record valve opening activities of bivalves. Various relationships with environmental variations have been elucidated through different types of metrics extracted from valvometric signals (e.g. valve opening, cyclicity, specific behaviours). Although automated data processing methods exist, many specific behaviours are still annotated manually. This study proposes an algorithm to detect and classify the behaviours performed by the great scallop (Pecten maximus) in two categories: jump-like (JL) behaviours and other behaviours (OBs). These two categories differ in the shape of their valvometric signal, JL being movements of high amplitudes associated with ‘displacement movements’ (rotation, swimming, jumping, flipping) and OB grouping all other movements of lower amplitudes (‘common movements’), such as partial closures, which are produced routinely. This algorithm has been developed and tested on 10 scallop valve opening time series recorded using fully autonomous valvometers based on the Hall effect principle. The algorithm detected 93.65% ± 5.5 of manually annotated behaviours produced by scallops, with a false detection rate of less than 6.3% ± 5.5. Classification performances vary according to the type of behaviour. JL behaviours and OBs were well classified at 83.72% ± 23.09 and 98.92% ± 1.80, respectively. Analysis of the algorithm's outputs, highlighting potential daily trends in the production of certain behaviours, shows their relevance for acquiring information on the biology of scallops. By providing an efficient and flexible detection and classification method, this study is a first step towards the automation of bivalve behaviour detection. This study also highlights the importance of simultaneously using Hall sensors and accelerometers to accurately classify the complex behaviours of mobile bivalves such as P. maximus.

Numerical study on the flow characteristics of ultrahigh pressure gas affected by valve opening time based a real gas model

Numerical study on the flow characteristics of ultrahigh pressure gas affected by valve opening time based a real gas model

Experimental and numerical investigation of cryogenic no-vent fill (NVF) process using adsorption on activated carbon

This paper describes a novel method of utilizing adsorption to a no-vent fill (NVF) process. A primary goal of the NVF process is to complete the fill process of cryogenic liquid within the allowable pressure of the receiver tank without venting. The use of physical adsorption at cryogenic temperature can suppress the pressure rise of the tank and facilitate the NVF process by adsorbing and storing the vapor at a high density. To prove the effects of adsorption on NVF, we conduct experimental tests of NVF processes of liquid nitrogen (LN2) using adsorption on activated carbon. The experimental apparatus used in tests consists of a 158 L receiver tank, a 180 L supply tank, an LN2 transfer line, and an adsorption storage system. The adsorption storage system, which has a volume of 2.2 L and contains 833 g of granular activated carbon, is precooled by a Stirling cryocooler before the NVF process starts. When the adsorption inlet valve is opened at 48 s, the peak pressure reduction of 3.2 kPa is proved experimentally in the sorption-assisted NVF process. Furthermore, a numerical model for the sorption-assisted NVF is established to investigate the adsorption-related parameters that affect NVF processes. The numerical model is developed by dividing it into NVF and adsorption models and is validated by comparing the predicted tank pressure and filling ratio with the measured data. For four experimental cases, the absolute error of the filling ratio is within 3.3 %, and the absolute error of the pressure is within 10.8 kPa. From numerical simulations, we identify four adsorption parameters: valve opening time, volume ratio of activated carbon and copper, adsorption tank volume, and valve opening degree. The simulation results demonstrate the applicability of adsorption effects for the NVF process.

Automated multi-functional system for the characterization of plate valves in reciprocating compressors

At present, there are two independent technologies and equipment for the test of the reciprocating compressor plate valve: the sealing test and blowing test. This method has single function and complicated test operation and may rely on theoretical calculations, which reduces the reliability of the test conclusion because the motion law of valve disk during opening and closing is extremely complicated. The existing test methods cannot meet the needs of more in-depth and accurate research, development and improvement of the plate valve. This study proposes a test device and method that can not only quantitatively test the performance of the plate valve but also qualitatively test the dynamic process of the suction valve plate, which can greatly reduce the testing time provide more intuitive and accurate valve plate motion tracks and valve paths. This paper takes the primary plate suction valve as the test object and adopts the automated multi-functional system to accurately obtain the valve’s sealing property, effective flow area, thrust coefficient, flow coefficient, drag drop, valve gap Mach number, initial opening pressure difference, maximum opening, and residence time of the valve plate on the valve lift guard to provide necessary data for valve design and performance evaluation. The test results of valve opening time are verified by industrial reciprocating compressor, which proves the accuracy and practicability of the system.

Physically-based control-oriented modeling for turbocharged stoichiometric spark-ignited engine with cooled EGR and flexible VVT systems

Accurate estimation and prediction of engine gas exchange system and in-cylinder conditions are critical for spark-ignited engine control and diagnostic algorithm development. In this paper, a physically-based, control-oriented model for a 2.8 l turbocharged, variable valve timing (VVT) and low pressure (LP) exhaust gas recirculation (EGR)-utilizing SI engine was developed. The model includes the impact of modulation to any combination of 10 actuators, including the throttle valve, compressor bypass valve, fueling rate, waste-gate, LP EGR valve, number of deactivated cylinders, intake valve open (IVO) timing, intake valve close (IVC) timing, exhaust valve open (EVO) timing and exhaust valve close (EVC) timing. The accuracy of the model in capturing engine dynamics was demonstrated by validating it against high-fidelity engine GT-Power simulation results for various drive cycles, particularly emphasizing elevated loads. In comparison to the open literature, novel contributions of the effort described in this paper includes in-cylinder gas composition modeling and turbine-out pressure estimation.

Study on the Effect of Parameter Sensitivity on Engine Optimization Results

The effects of six control parameters, intake valve opening timing (IVO), exhaust valve opening timing (EVO), compression ratio (CR), engine speed, intake temperature, and intake pressure on engine output power, indicated specific fuel consumption (ISFC), and nitrogen oxides (NOx) emissions, are analyzed through engine simulation. The six parameters were categorized into two groups based on the degree of influence: high influence (EVO, speed and intake pressure) and low influence (CR, IVO and intake temperature). The relationship between these two groups of parameters and power, ISFC and NOx emissions was explored. Optimization was carried out for each of the two groups of parameters, and the optimization of the high impact parameters resulted in a higher diversity and wider distribution of the solution set. On the other hand, the optimization of the low-impact parameters resulted in a more concentrated distribution of the solution set, while better reflecting the trade-off between the optimization objectives. For the optimal solutions for both sets of parameters, the high-impact parameters provided significant optimization performance compared to the standard operating conditions. Although power and ISFC were optimized, the optimal solution for the low-impact parameter performed poorly with a significant increase in NOx emissions. Therefore, the parameters should be evaluated for optimization using high impact parameters to improve engine performance.

Investigation of the control strategy for hydrogen addition in all operating conditions of a high compression ratio liquid methane heavy-duty engine

The hydrogen addition to liquid methane gas (LMG) engines based on the rational control strategy is considered to be a promising approach to improve the performance of LMG engines. However, the current studies are limited to a few operating points. To comprehensively develop a control strategy of hydrogen addition for high compression ratio LMG engines, the effects of hydrogen addition on the emissions, combustion, and performance of an LMG engine are experimentally investigated under all operating conditions in this study. Furthermore, to achieve the optimal performance of the hydrogen-LMG engine with the optimal hydrogen blending, the coupled simulation model of MATLAB/Simulink and GT-Power is established based on the test bench, and the multiple operating parameters of the calibrated numerical model are optimized by using genetic algorithm. The results show that the maximum increases in the brake thermal efficiency with increasing hydrogen energy share (HES) are 1.6, 0.9 and 0.6 percentage points under low, medium and high loads, respectively. Correspondingly, the maximum reduction in EBSFC under low, medium and high loads is 6.5 %, 2.2 % and 1.4 %, respectively. The ignition delay is reduced and the combustion is promoted with the increase in HES. As a result, the cylinder pressure and HRR rise faster and reach a higher peak earlier. In addition, the 50 % combustion location is advanced and the 10–90 % combustion duration is shortened. In terms of emissions, the increasing HES promotes the NOx emissions and reduces the HC emissions. Especially at medium and high loads, the NOx emissions rise sharply with increasing HES. It is desirable that HES should not exceed 15 %, 4 % and 2 % at low, medium and high loads, respectively. In addition, by co-optimizing the intake valve opening timing, exhaust valve opening timing and the spark angle, the BSFC of the hydrogen-LMG engine with the optimal HES under 1200 rpm and BMEP of 6 bar is still improved by 2.2 %. This study provides new insights to further explore the energy-saving potential of hydrogen-LMG engines.

Experiments and numerical analysis of the dynamic flow characteristics of a pump−pipeline system with entrapped air during start-up

A pump−pipeline experiment platform is designed and built for exploring the dynamic flows in a pipe-conveying fluid with entrapped air, and a corresponding CFD simulation is executed based on the volume-of-fluid (VOF) model. The transient flow characteristics of the entrapped air in pipelines under different pump and valve working conditions are studied by experimental and numerical approaches. The experimental data and simulation results are in good agreement. Both of them show that the pressure impact can be mitigated by increasing the air volume ratio (air volume/pipe volume) or the valve opening time. Two types of the air–water interfaces, a clear interface and a broken interface, appear in the process of air pressurization to the peak pressure as the flow rate rises and the valve opening time decreases. The influence of the flow rate, air volume and valve opening time on the peak pressure and arrival time are investigated, and a corresponding equation with respect to the dimensionless parameters is proposed for the pressure prediction of a system with entrapped air during start-up.

Tests on Hydraulic Props Equipped with Yield Valves at Dynamic Load Modelling a Rock Burst

The article presents the results of tests on SHC-40 hydraulic props equipped with two types of valve blocks: standard (with spring steel cylinder) and BZG-2FS (with gas spring). The research was conducted using impact mass of 4,000 kg and with extreme dynamic load of free fall impact mass of 20,000 kg released from different heights h. The dynamic tests involved a camera with the speed of image capture up to 1,200 frames/sec, which made it possible to register the stream of liquid at the dynamic load and to determine the valve opening time. The study conducted on SHC-40 NHR10 props equipped with two types of valve blocks: a standard and the BZG-2FS fast acting relief, showed that the prop with the BZG-2FS block is more suitable and more effective in the case of areas with high risk of mining tremors and rapid stress relief of a seam. Research methodology developed in the Central Mining Institute combines digital recording technique of pressure in a prop and fast registration of the images, and allows to acquire more accurate analysis of dynamic phenomena in the prop during testing.

Wrist ballistocardiography and invasively recorded blood pressure in healthy volunteers during reclining bike exercise.

Objective: Ballistocardiogram (BCG) features are of interest in wearable cardiovascular monitoring of cardiac performance. We assess feasibility of wrist acceleration BCG during exercise for estimating pulse transit time (PTT), enabling broader cardiovascular response studies during acute exercise and improved monitoring in individuals at risk for cardiovascular disease (CVD). We also examine the relationship between PTT, blood pressure (BP), and stroke volume (SV) during exercise and posture interventions. Methods: 25 participants underwent a bike exercise protocol with four incremental workloads (0W, 50W, 100W, and 150W) in supine and semirecumbent postures. BCG, invasive radial artery BP, tonometry, photoplethysmography (PPG) and echocardiography were recorded. Ensemble averages of BCG signals determined aortic valve opening (AVO) timings, combined with peripheral pulse wave arrival times to calculate PTT. We tested for significance using Wilcoxon signed-rank test. Results: BCG was successfully recorded at the wrist during exercise. PTT exhibited a moderate negative correlation with systolic BP (ρSup = -0.65, ρSR = -0.57, ρAll = -0.54). PTT differences between supine and semirecumbent conditions were significant at 0W and 50W (p < 0.001), less at 100W (p = 0.0135) and 150W (p = 0.031). SBP and DBP were lower in semirecumbent posture (p < 0.01), while HR was slightly higher. Echocardiography confirmed association of BCG features with AVO and indicated a positive relationship between BCG amplitude and SV (ρ = 0.74). Significance: Wrist BCG may allow convenient PTT and possibly SV tracking during exercise, enabling studies of cardiovascular response to acute exercise and convenient monitoring of cardiovascular performance.

Electrocardiogram to Determine Mitral and Aortic Valve Opening and Closure.

Knowledge of the timing of cardiac valve opening and closing is important in cardiac physiology. The relationship between valve motion and electrocardiogram (ECG) is often assumed, however is not clearly defined. Here we investigate the accuracy of cardiac valve timing estimated using only the ECG, compared to Doppler echocardiography (DE) flow imaging as the gold standard. DE was obtained in 37 patients with simultaneous ECG recording. ECG was digitally processed and identifiable features (QRS, T, P waves) were examined as potential reference points to determine opening and closure of aortic and mitral valves, as compared to DE outflow and inflow measurement. Timing offset of the cardiac valves opening and closure between ECG features and DE was measured from derivation set (n = 19). The obtained mean offset in combination with the ECG features model was then evaluated on a validation set (n = 18). Using the same approach, additional measurement was also done for the right sided valves. From the derivation set, we found a fixed offset of 22 ± 9 ms, 2 ± 13 ms, 90 ± 26 ms, and -2 ± -27 ms when comparing S to aortic valve opening, Tend to aortic valve closure, Tend to mitral valve opening, and R to mitral valve closure respectively. Application of this model to the validation set showed good estimation of aortic and mitral valve opening and closure timing value, with low model absolute error (median of the mean absolute error of the four events = 19 ms compared to the gold standard DE measurement). For the right-sided (tricuspid and pulmonic) valves in our patient set, there was considerably higher median of the mean absolute error of 42 ms for the model. ECG features can be used to estimate aortic and mitral valve timings with good accuracy as compared to DE, allowing useful hemodynamic information to be derived from this easily available test.

Assessment of a synergistic control of intake and exhaust VVT for airflow exchange, combustion, and emissions in a DI hydrogen engine

Variable valve timing (VVT) and Miller cycle are advanced technologies employed to optimize engine performance by improving airflow exchange, which are seldom investigated based on the direct-injection (DI) hydrogen engine. The objective of this study is to assess the effects of intake valve closing (IVC) and exhaust valve opening (EVO) timing on the gas exchange performance, combustion, and emissions of a DI hydrogen engine, after which a synergistic control strategy of IVC and EVO timing is proposed. This work is conducted under wide-open throttle and 1500 rpm. The results indicate that the synergistic control of IVC and EVO timing can increase volumetric efficiency by more than 40%, enhance gas exchange performance, shorten combustion duration, and reduce cyclic variation, resulting in approximately 43.15% brake thermal efficiency. Furthermore, brake mean effective pressure can be increased by more than 60% and NO emissions are controlled to less than 20 ppm by optimizing valve timings.

Development of a Zero-Dimensional Model for a Low-Speed Two-Stroke Marine Diesel Engine with Exhaust Gas Bypass and Performance Evaluation

Most large commercial vessels are propelled by low-speed two-stroke diesel engines due to their fuel economy and reliability. With increasing international concern about emissions and the rise in oil prices, improvements in engine efficiency are urgently needed. In the present work, a zero-dimensional model for a low-speed two-stroke diesel engine is developed that considers the exhaust gas bypass and geometry structures for the gas exchange model. The model was applied to a low-speed two-stroke 7G80 ME-C9 marine diesel engine and validated with engine shop test data, which consisted of the main engine performance parameters and cylinder pressure diagrams at different loads. The simulation results were in good agreement with the experimental data. Thus, the model has the ability to predict engine performance with good accuracy. After model validation, the variations in compression ratio, fuel injection timing, exhaust gas bypass valve opening portion, exhaust valve opening timing, and exhaust valve closing timing effects on engine performance were tested. Finally, the influence level of different parameters on engine performance was summarized, which can be used as a reference to determine the reasons for high fuel consumption in some cases. The developed engine performance model is considerable in digital twins for performance simulation, health management, and optimization.

Evaluation of the variable valve timing strategy in a direct-injection hydrogen engine with the Miller cycle under lean conditions

The favorable physicochemical characteristics of hydrogen make it an excellent alternative fuel for IC engines. Compared with hydrogen port injection, hydrogen direct injection provides multiple degrees of freedom for injection strategies and mixture formation, which can effectively suppress abnormal combustion and enhance engine performance. Variable valve timing (VVT) and the Miller cycle, as advanced and effective means of improving engine performance, are less investigated based on a direct-injection (DI) hydrogen engine. Hence, to optimize the performance of a DI hydrogen engine, strategies of the Miller cycle and VVT are introduced. In this work, a 1.5 L direct-injection engine with a VVT system was employed to evaluate the effects of the Miller cycle, intake valve closing (IVC) timing, and exhaust valve opening (EVO) timing on the airflow exchange process, in-cylinder charge characteristics, heat release process, dynamics and emission characteristics. The engine speed was stabilized at 1400 rpm and the strategies of lean combustion and late injection were used. The main results are as follows. As the IVC timing is delayed, the ratio of pumping mean effective pressure to indicated mean effective pressure (PMEP/IMEP) first decreases and then slightly increases, and the engine tends to achieve a high level of brake thermal efficiency (BTE) when PMEP/IMEP is lower. The optimization of intake and exhaust VVT can shorten combustion duration and reduce cyclic variation by increasing volumetric efficiency and improving mixture distribution at ignition timing. Furthermore, the engine reaches 42.22% BTE and a high level of brake mean effective pressure by the cooperative control of IVC and EVO timing. NOx emissions can be controlled below 100 ppm by employing the synergistic effect of the Miller cycle and VVT. It is worth mentioning that exhaust VVT as a way to compensate for the performance of the DI hydrogen engine with the Miller cycle should not be ignored.

Simulation of Sequential Turbocharging Switching Control System for Low Speed Diesel Engines

In order to study the sequential turbocharging switching process of low-speed diesel engine, this paper uses GT-power software to establish a simulation model of sequential turbocharging low-speed diesel engine. It is enhanced and improved into a model of a sequential supercharged diesel engine. Modules such as load, governor, valve control, and surge margin are set up in the simulation model. Then parameters such as switching speed, valve opening time and response time are set in the model. Through the above preparations, the thesis has carried out the simulation calculation of the sequential supercharging transient switching process and verified the rationality of the setting parameters and the accuracy of the module setting. This provides a certain reference for the valve control strategy of the sequential supercharging switching system of low-speed diesel engines.

Abstract 12821: Progressive Improvement in Left Ventricular Performance Associated With Progressive Regional Dyssynchrony

Background : We have shown that non-excitatory epicardial stimulation (NES) increases measures of cardiac function mediated by local release of norepinephrine. In this further investigation we determined whether NES is accompanied by improved indices of left ventricular (LV) performance, reflected in PV loops and timing of aortic valve opening and closing. Methods : Anesthetized pigs (n=6) were instrumented with a LV high-fidelity pressure/volume conductance transducer, thoracic aortic pressure transducer, left atrial (LA)/ LV epicardial electrodes, and sonomicrometer segment length (SL) gauges placed proximal (lateral base) and distal (posterior mid LV) to the LV stimulation site. During constant LA pacing, LV pulses (0.8ms, 2-3x threshold volts) were applied during the absolute refractory period for 3 minutes (3x), before and after β-receptor blockade (BB, metoprolol). Data were analyzed at baseline, and at an estimated 30%, 60% and 100% of developed ventricular dyssynchrony (DVD) contraction pattern. Results: Consistent with earlier findings, NES resulted in an early shortening and relaxation pattern of the proximal SL manifest as an 80% decrease in the LVP vs. SL loop area in the absence of change in the remote segment. This was accompanied by an increase in peak systolic pressure and LV dP/dt max. Although NES did not change the area of the LVP vs. LV volume loop (stroke work) or alter the interval from LV electrical activation (R wave) to the onset of LV pressure increase, aortic valve opening occurred up to 14.1 ± 2.8 ms earlier (p &lt;0.01) compared to baseline. The duration of an open aortic valve slightly increased (6.0 ± 3.9 ms) whereas ejection duration from valve opening to peak Pao decreased 18.2 ± 3.0 ms (p &lt; 0.01). Conclusion : These findings demonstrate that NES elicits a local contractile dysynchrony resulting in an enhanced cardiac inotropic state characterized by more rapid global LV contraction with earlier aortic valve opening with no change in stroke work.