High Impulse Research Articles

Electrochemical Properties of CrAl/CrAlN and CrAl/CrAlN-(a-CNx) Multilayer Deposited by High Power Impulse Magnetron Sputtering

Electrochemical Properties of CrAl/CrAlN and CrAl/CrAlN-(a-CNx) Multilayer Deposited by High Power Impulse Magnetron Sputtering

One-Dimensional Steady-State Thermal Model of CNTP Reactor

A more advanced form of nuclear propulsion known as centrifugal nuclear thermal propulsion (CNTP) promises increased propellant temperatures that could lead to a high specific impulse in the range of 1500 to 1800 s with hydrogen. This design has the potential of opening opportunities to perform missions to destinations much farther than currently possible. However, the CNTP concept poses many engineering challenges due to the nuclear fuel operating at high temperature in a liquid phase. A one-dimensional, steady-state thermal model of the liquid uranium fuel has been constructed to understand the limitations of this concept and the potential design considerations. Three related basic designs are considered, and key design parameters are varied in order to predict the temperature levels and void fractions across the liquid uranium pool.

Ion- and temperature-induced 3-dimensional nanoscale patterning in Ti1-xAlxN deposited by High Power Impulse Magnetron Sputtering

We report on surface-driven self-organization in the TiN-AlN binary system during ion-assisted deposition at elevated temperatures. With an Al:Ti ratio slightly above the boundary of stable cubic growth, various morphologies from single-phase films to highly ordered two-phase films with v-shaped and oblique, striped structures were obtained. The high metal ion fractions and high ion energies obtained by High Power Impulse Magnetron Sputtering result in unique morphologies that are not accessible by conventional magnetron sputtering. A comprehensive structural and chemical analysis of the two-phase films is presented to enlighten the mechanism of phase separation and crystallographic orientation evolution.

Impulsivity Moderates the Association Between Anxiety and Problem Gambling Among Canadian Undergraduates.

Tension reduction theory suggests anxious people gamble to cope with negative affect. Literature demonstrates mixed associations between anxiety and gambling behaviours, hence, the important of examining moderators. This study examined how impulsivity moderated anxiety and problem gambling as well as gambling to cope. Given key gender differences, moderation was examined across genders. A sample of 484 undergraduate students who endorsed gambling behaviours completed anxiety, impulsivity, and problem gambling measures. Results showed men with higher levels of anxiety scored higher on problem gambling at both high (B = 0.706, SE = 0.073, p < 0.0001, f2 = 0.20) and low (B = 0.262, SE = 0.103, p = 0.01, f2 = 0.01) impulsivity, though the effect sizes were much larger for men with high impulsivity. This moderation effect was not found in women (B = 0.000, SE = 0.009, p = 0.959). Results showed men with higher levels of anxiety scored higher on coping motives for gambling at both high (B = 0.253, SE = 0.046, p < 0.0001, f2 = 0.06) and low B = 0.141, SE = 0.063, p = 0.026, f2 = 0.01) impulsivity, though the effect sizes were larger for men with high impulsivity. Again, this moderation effect was not found in women (B = - 0.101, SE = 0.006, p = 0.100). Findings from this may help inform impulsivity-focused interventions, such as strengthening impulse control and instilling more adaptive coping strategies to lower gambling risk among university men.

Optimization of Interplanetary Trajectory for Direct Fusion Drive Spacecraft

The Direct Fusion Drive (DFD) technology, which is being developed at present, will allow fast and affordable interplanetary travel. This is a result of the very high specific impulse and the low specific mass of DFD thrusters which outperform more conventional Nuclear Electric Propulsion (NEP), with which it shares the ability of providing a low (albeit higher than in the case of NEP) continuous thrust. It is well known that, to optimize the payload fraction, the thruster should operate in Variable Exhaust Velocity (VEV) mode and that the lower is the specific mass, the higher should be the maximum specific impulse the thruster can produce. A low thrust interplanetary travel, from the orbit around the starting planet to the orbit around the destination planet, can be considered as made of three parts: a first planetocentric phase, a second heliocentric phase and finally a third planetocentric phase; in all of them the trajectory is a sort of a spiral, but while in the first and third the spacecraft makes several (or even a large number) turns about the two planets, the second consists of a fraction of a turn about the Sun. In the first and last one the optimal specific impulse is not much variable and should remain quite low, while in the second one it must go through large variations, reaching a very high value at roughly midway between the planets. To show the potentialities of DFD, three typical fast missions are studied: to the Moon, to Mars and to Titan, showing that this propulsion device will allow humans to reach practically the whole solar system in a reasonable time. Keywords: Interplanetary travel, Human Mars Exploration, Direct Fusion Drive, Trajectory Optimization, Specific Impulse Optimization

Optimization of Interplanetary Trajectory for Direct Fusion Drive Spacecraft

The Direct Fusion Drive (DFD) technology, which is being developed at present, will allow fast and affordable interplanetary travel. This is a result of the very high specific impulse and the low specific mass of DFD thrusters which outperform more conventional Nuclear Electric Propulsion (NEP), with which it shares the ability of providing a low (albeit higher than in the case of NEP) continuous thrust. It is well known that, to optimize the payload fraction, the thruster should operate in Variable Exhaust Velocity (VEV) mode and that the lower is the specific mass, the higher should be the maximum specific impulse the thruster can produce. A low thrust interplanetary travel, from the orbit around the starting planet to the orbit around the destination planet, can be considered as made of three parts: a first planetocentric phase, a second heliocentric phase and finally a third planetocentric phase; in all of them the trajectory is a sort of a spiral, but while in the first and third the spacecraft makes several (or even a large number) turns about the two planets, the second consists of a fraction of a turn about the Sun. In the first and last one the optimal specific impulse is not much variable and should remain quite low, while in the second one it must go through large variations, reaching a very high value at roughly midway between the planets. To show the potentialities of DFD, three typical fast missions are studied: to the Moon, to Mars and to Titan, showing that this propulsion device will allow humans to reach practically the whole solar system in a reasonable time. Keywords: Interplanetary travel, Human Mars Exploration, Direct Fusion Drive, Trajectory Optimization, Specific Impulse Optimization

Effects of key parameters on performance of a pre-cooled core engine based on the closed helium cycle

A pre-cooled combined engine based on a closed helium (He) cycle offers high specific thrust and high specific impulse. Therefore, evaluation of the performance of such an engine is crucial for engine applications and key technology research. This study employs an analytical approach to investigate the effects of key parameters on the performance of a pre-cooled core engine, assuming a perfect gas model. The findings revealed that the specific thrust and specific impulse of the pre-cooled core engine are related to the pressurized coefficient of the airflow passage and equivalence ratio (ER). An increase in the pressurized coefficient leads to an increase in both specific thrust and specific impulse. However, within a certain range, although the specific thrust is positively correlated with the ER, the specific impulse is greatly reduced. With specific component parameters and a fixed thermodynamic cycle, a minimum ER exists, which satisfies the cycle-matching requirement. Moreover, the value of the minimum ER is related to the closed-cycle efficiency. For a pre-cooled core engine with a simple closed He cycle, the minimum ER is approximately 2.5–3.5.

Influence of the magnetic field on the extension of the ionization region in high power impulse magnetron sputtering discharges

The high power impulse magnetron sputtering (HiPIMS) discharge brings about increased ionization of the sputtered atoms due to an increased electron density and efficient electron energization during the active period of the pulse. The ionization is effective mainly within the electron trapping zone, an ionization region (IR), defined by the magnet configuration. Here, the average extension and the volume of the IR are determined based on measuring the optical emission from an excited level of the argon working gas atoms. For particular HiPIMS conditions, argon species ionization and excitation processes are assumed to be proportional. Hence, the light emission from certain excited atoms is assumed to reflect the IR extension. The light emission was recorded above a 100 mm diameter titanium target through a 763 nm bandpass filter using a gated camera. The recorded images directly indicate the effect of the magnet configuration on the average IR size. It is observed that the shape of the IR matches the shape of the magnetic field lines rather well. The IR is found to expand from 10 and 17 mm from the target surface when the parallel magnetic field strength 11 mm above the racetrack is lowered from 24 to 12 mT at a constant peak discharge current.

Temporal, spatial and spectroscopic study of plasma emission on Cu target in bipolar HiPIMS

Bipolar high power impulse magnetron sputtering introduces new possibilities to affect positive ions created during the negative discharge pulse in order to tailor thin films with specific parameters. This paper studies plasma emission in different experimental conditions during different phases of the positive pulse with spectral, spatial and temporal resolution. It is found that predominantly the working gas gives rise to plasma emission during the positive pulse. The plasma emission is observed only in regions of low magnetic confinement, forming a ‘mushroom-like’ shape in the middle of the target or a ‘dome-like’ shape on the outer parts of the target. An explanation of the discharge kinetics is proposed based on the acquired data.

Understanding the Risks and Individual Difference Factors Associated with Engagement in Monetised (Play-to-Earn) Gaming

AbstractPlay-to-earn (P2E) is a new form of monetised gaming based on blockchain and crypto-currency technology. Such games offer opportunities to combine gaming with speculative investment through the purchase of tradable in-game currencies and assets (non-fungible tokens). In this paper, we investigate the profile of people most likely to be attracted to this emerging form of gaming. A sample of 560 participants aged between 18-65 (M = 28.3, SD = 8.3) were recruited via Prolific to complete an online survey that included measures of gaming (Petry’s Internet Gaming Disorder Scale) and gaming risk (Problem Gambling Severity Index), measures of gaming motivation and impulsivity. Other existing engagement in gaming monetization as well as digital asset ownership was also assessed. P2E interest was associated with higher gambling risk scores, but not with internet gaming disorder. P2E gamers also scored higher on extrinsic motivation and monetised gaming was generally associated with higher impulsivity. The results suggest that P2E may be attractive to those with a pre-existing interest in financially risky activities. Policy implications include the increasing need to monitor the growth of digital asset technology and the increasing convergence of gambling, financial speculation and gaming and the potential for increasing financial harm in gaming populations.

Blast response of bioinspired nacre-like staggered composite plates combined with steel and polyurea

Inspired by the mother-of-pearl layered structure, a multilayered staggered composite plate (SCP) consisting of steel and polyurea was designed, and its dynamic responses under high impulse loads were investigated. The precision of the numerical model design and parameter selection was first validated by the blast experiment results of a normal composite plate (NCP). The center point displacement, velocity, and acceleration of the NCP and SCP were compared, and the corresponding values for the SCP decreased by 38.43%, 5.77%, and 63.30%, respectively. The backplate overpressure and intra-plate stress of the SCP were reduced by 86.67% and 81.48%, respectively. The SCP greatly improved the energy absorption efficiency through the phenomena of interlocking, friction, and slippage between layers. As the delamination number of the SCP increased, both the displacement, velocity, and acceleration of the center point and the energy absorption efficiency increased. When the polyurea layer thickness ratio and the steel table thickness ratio were 0.1675 and 0.125, respectively, the deformation response and energy absorption efficiency of the SCP tended to be similar. Finally, the effective modulus of elasticity of the SCP was analyzed based on a shear-lag model.

Microwave controlled ignition and combustion characteristics of ADN-based ionic liquid propellant with fast response and environmental friendliness

The ADN-based ionic liquid propellants have been successfully implemented in liquid rocket engines, owing to high specific impulse and thrust, low toxicity and environmental friendliness. However, the traditional catalyst ignition of ADN-based propellant suffers from the problems of catalyst deactivation problems in the heating process. Microwaves could interact with the material holistically due to excellent penetration ability. Compared with solid materials, ionic liquids are natural microwave receptors on account of great polarity. To date, the possibility of microwave ignition of ionic liquid materials has not been explored. In this work, two kinds of ionic liquids: ADN and [AMIM][DCA] were used as oxidant and fuel of liquid propellant to achieve the maximum microwave absorption effect. The microwave controlled ignition and combustion of ADN-based liquid propellant was first realized and systematically studied. Compared to single component, the heat release, gas production, conductivity and heating rate of the mixed system was greatly enhanced. The sample (ADN/[AMIM][DCA] 10%) was successfully ignited by microwaves, displaying a decreased ignition delay time at higher power inputs. The ignition was generated in the gas phase and rapidly diffused into the solution, and the extinguishment was highly consistent with the input cessation of microwaves. The ignition delay was significant reduced in repeated ignition, resulted from the faster moving speeds of ions. The successful realization of microwave controlled ignition and combustion of ADN-based IL propellant will broaden the scope of their applications in space fuel and provide a new direction for the reform of liquid engines.

Impulsivity in Major Depressive Disorder Patients with Suicidal Ideation: Event-related Potentials in a GoNogo Task.

: Suicidal ideation is one of the strongest predictors of suicide, and its relevance to impulsivity in depressed patients has been accumulated. Furthermore, high impulsivity patients show the attenuation of the Nogo amplitude in the GoNogo event-related potential (ERP). The purpose of the current study is to determine the correlation of Nogo ERP to the suicidal ideation depending on the condition of its presence or absence in major depressive disorder (MDD) patients. : A total 162 participants (104 patients with suicidal ideation, 31 patients without suicidal ideation, and 27 healthy controls) were recruited, and performed GoNogo tasks during the electroencephalogram measurement. Depression, anxiety, suicidal ideation and impulsivity were assessed by self-rating scales. The clinical measures, behavioral data and Nogo ERP were compared among groups. : The MDD with suicidal ideation (SI) group showed significantly decreased Nogo P3 amplitudes compared to MDD without SI (Fz and Cz electrodes) and control group (all electrodes). The MDD with SI group also had significantly low accuracy of both Go and Nogo trails, compared to the MDD without group. The Nogo P3 amplitudes showed the negative relation to the scores of impulsivity, depression, anxiety and SI. : Our results concluded that the Nogo P3 ERP amplitude was decreased in MDD patients with SI compared to MDD patients without SI and controls. These findings suggest that the decreased Nogo P3 amplitude is the one of the candidate biomarker for impulsivity in MDD patients to evaluating SI.

The moderation effect of mentalization in the relationship between impulsiveness and aggressive behavior.

Aggressive behavior is a growing problem across many contexts. Thus, searching for its predictors is important. The aim of the current study was to analyze the moderator effect of mentalization in the relationship between impulsiveness and both verbal and physical aggressive behavior, using a sample of 583 participants gathered from the general Spanish population (MAge = 34.60, SDAge = 12.99). In our sample, 182 were male and 401 were female. The results showed significant bivariate relationships among aggression, impulsiveness, and mentalization. Moderation structural equation modeling (MSEM) showed a significant moderation effect, so whereas the value of mentalization is not relevant in cases of people with low impulsiveness, high mentalization abilities allow those people with high impulsiveness to behave less aggressively than people with high impulsiveness and low mentalization abilities. Practical implications and limitations of the study are discussed.

Associations Between Personality Traits and Energy Balance Behaviors in Emerging Adulthood: Cross-Sectional Study.

Internalizing and externalizing personality traits are robust risk factors for substance use and mental health, and personality-targeted interventions are effective in preventing substance use and mental health problems in youth. However, there is limited evidence for how personality relates to other lifestyle risk factors, such as energy balance-related behaviors, and how this might inform prevention efforts. This study aimed to examine concurrent cross-sectional associations between personality traits (ie, hopelessness, anxiety sensitivity, impulsivity, and sensation seeking) and sleep, diet, physical activity (PA), and sedentary behaviors (SB), 4 of the leading risk factors for chronic disease, among emerging adults. Data were drawn from a cohort of young Australians who completed a web-based, self-report survey in 2019 during early adulthood. A series of Poisson and logistic regressions were conducted to examine the concurrent associations between the risk behaviors (sleep, diet, PA, and sitting and screen time) and personality traits (hopelessness, anxiety sensitivity, impulsivity, and sensation seeking) among emerging adults in Australia. A total of 978 participants (mean age 20.4, SD 0.5 years) completed the web-based survey. The results indicated that higher scores on hopelessness were associated with a greater daily screen (risk ratio [RR] 1.12, 95% CI 1.10-1.15) and sitting time (RR 1.05, 95% CI 1.0-1.08). Similarly, higher scores on anxiety sensitivity were associated with a greater screen (RR 1.04, 95% CI 1.02-1.07) and sitting time (RR 1.04, 95% CI 1.02-1.07). Higher impulsivity was associated with greater PA (RR 1.14, 95% CI 1.08-1.21) and screen time (RR 1.06, 95% CI 1.03-1.08). Finally, higher scores on sensation seeking were associated with greater PA (RR 1.08, 95% CI 1.02-1.14) and lower screen time (RR 0.96, 95% CI 0.94-0.99). The results suggest that personality should be considered when designing preventive interventions for lifestyle risk behaviors, particularly in relation to SB, such as sitting and screen time. Australian New Zealand Clinical Trials Registry ACTRN12612000026820; https://tinyurl.com/ykwcxspr.

Self-control and unhealthy body weight: The role of impulsivity and restraint

We examine the relationship between trait self-control and body weight. Data from a population representative household survey reveal that limited self-control is strongly associated with both unhealthy body weight and poorer subjective weight-related well-being. Those with limited self-control are characterized by reduced exercising, repeated dieting, unhealthier eating habits, and poorer nutrition. We propose an empirical method to isolate two facets of self-control limitations—high impulsivity and low restraint. Each has differential predictive power. Physical activity, dieting, and overall body weight are more strongly associated with restraint; impulsivity is relatively more predictive of when, where, and what people eat.

Regularized direct method for low–thrust trajectory optimization: Minimum–fuel transfer between cislunar periodic orbits

Low–thrust propulsion systems of high specific impulse are advantageous in the fuel efficiency. The fuel expenditure is further reduced together with optimization techniques though fuel–optimal low–thrust trajectories result in a discontinuous bang–bang control structure that can cause numerical difficulties. The present paper introduces regularized formulations into the direct multiple shooting method of minimizing fuel expenditure for low–thrust spacecraft trajectories. Instantaneous velocity changes approximating low–thrust maneuvers are expressed by regularized variables based on the Levi–Civita or Kustaanheimo–Stiefel transformation. The new formulation removes singularities due to null thrust impulses from derivatives of an objective function and constraints. The method automatically and robustly finds fuel–efficient bang–bang control structures for multi–revolutional transfers between periodic orbits in the Earth–Moon circular restricted three–body problem.

Adaptive LDPC coded high data rate based IR-UWB combined with VMIMO system for vehicular communication links

The automotive industry is developing significantly with the evolution of vehicular networks, intelligent transportation systems, and autonomous cars. These technologies are made achievable by recent advances in software, hardware, and communication systems, along with various applications and standardization efforts. On the other side, many impairments have existed due to these evolving, limiting the process of vehicular networks. So, this paper proposes an implementation of adaptive LDPC-coded, high data rate-based Impulse Radio-Ultra Wide Band (IR-UWB) combined with Virtual Multiple Input Multiple Output (VMIMO) systems for Vehicle-to-Vehicle (V2V) and Vehicle-to-Infrastructure (V2I) wireless communications. Furthermore, they are merged with orthogonal pulse shaping using a modified Hermite pulse. Besides, the paper compares Zero-Forcing (ZF) and Minimum Mean Square Error (MMSE) detection techniques. To enhance and mitigate the existing impairments facing the vehicular networks. The proposed system’s performance is evaluated using both techniques, utilizing Bit Error Rate (BER), processing time, and resultant throughput analysis for both channel models. The simulation results include Non-Line of Sight (NLoS) and Line of Sight (LoS) scenarios for both channel models. Moreover, the simulation considers the effect of path loss and noise on the transmitted signal. In addition, the recent LDPC decoding algorithm termed “Modified Implementation Efficient Reliability Ratio Weighted Bit Flipping” (MIERRWBF) is evaluated through all latter channel models. At last, a novel adaptive LDPC decoder is proposed to further enhance the performance of all vehicular communication links under study. Consequently, the paper proposed an integrated adaptive LDPC-coded high data rate communication system to enhance vehicular communications using VMIMO mixed with modified Hermite orthogonal pulse shaping and deploying the MMSE recommended detection technique.

Ionization of sputtered material in high power impulse magnetron sputtering plasmas—comparison of titanium, chromium and aluminum

The ionization of sputtered species in high power impulse magnetron sputtering of titanium, chromium, and aluminum targets is analyzed using Abel-inverted spectroscopic imaging to locate the position of ionization. From the spatial emission of neutrals, it is deduced that most of the sputtered titanium particles become ionized within 0.5 mm distance from the target, whereas sputtered aluminum or chromium can travel much further through the discharge before ionization occurs. Probe measurements reveal the reason for this difference to be the unusually high electron temperature of around 4.5 eV for titanium compared to 2.6 eV and 1.5 eV for aluminum and chromium as the target material, respectively. These probe measurements are then compared to a global model derived from the ionization region model. Excellent agreement between model and measurements can be reached, but only if the transport physics for the confinement of the species is adjusted. Using the model, the difference between the three discharges can be traced back to be mostly caused by the sputter yield. Thus, we propose that ionization in discharges with low-yield materials should generally be expected to occur closer to the target surface, leading the ions to be affected more strongly by the electric field across the magnetic trap region, resulting in a more severe deposition rate loss compared to high-yield materials.

Construction of Cr coatings with different columnar structure on Zircaloy-4 alloys to optimize the high-temperature steam oxidation behavior for accident tolerant fuel claddings

To optimize the oxidation behavior of chromium-coated Zircaloy-4 alloys under 1200 °C high-temperature steam for accident tolerant fuel (ATF) claddings, Cr coatings with different columnar structure are constructed by changing bias voltage using high power impulse magnetron sputtering and corresponding microstructure, mechanical and high-temperature steam oxidation properties are studied systematically. With the bias voltage increase from 0 V to − 150 V, the microstructure of Cr coatings changes from porous columnar structure to compact columnar structure. Especial for bias voltage is − 90 V, the tiny compact grains uniform distribute on the surface micrographs and optimal compact columnar structure are observed on the cross-section micrographs. The hardness and elastic modulus of as-prepared Cr coatings increase firstly and then decrease, the hardness of Cr coatings with optimal compact columnar structure is 8.65 GPa, which is elevated ∼2.28 times than Cr coatings with porous columnar structure. 1200 °C high-temperature steam oxidation test results show an interesting phenomenon that the thickness of Cr layer reduces initial and then increase with the exposure time prolong from 1 h to 4 h. The main steam oxidation mechanism, in the early oxidation stage, is formation the compact Cr2O3 oxide layer. Then, with the exposure time extend, the reduction reaction plays the significant part for steam oxidation mechanism, which is consumption of outmost Cr2O3 oxide layer and formation of subsurface Cr layer. The construction of Cr coatings with compact columnar structure and relevant oxidation mechanism are expected to offer a new idea for improving 1200 °C steam oxidation resistance of chromium-coated Zircaloy-4 alloys.