Small Cylinder Research Articles

Evaluation of average cross‐polarised scattered field from a PEMC cylinder of the random radius with uniform/normal distribution

The average scattered field from a random perfect electromagnetic conductor (PEMC) is investigated. First, a very small cylinder is considered and analytical expressions for average scattered field are written using a small approximation of cylindrical wave functions. It is shown that co-polarised average scattered field from a very small PEMC cylinder depends on only zeroth-order scattering coefficient, whereas higher-order coefficients also contribute to cross-polarised average scattered field. Moreover, the average scattered field from a very small PEMC cylinder can be written in terms of average scattered field of a very small perfect electric conductor (PEC) cylinder. The second case deals with small and large radii. In this case, it is not possible to write down analytical expressions for the average field, the numerical average is done. For small PEMC cylinder, it has been observed that average co-polarised scattered field is equal to the scattered field from a cylinder with a mean radius. This is not true in case of cross-polarised scattered field and the difference can be seen for most of the scattering angles. In case of large PEC/PEMC cylinders, it is observed that the average scattered field is almost equal to the scattered field from a cylinder with a mean radius.

Ceramics from Municipal Waste Incinerator Bottom Ash and Wasted Clay for Sensible Heat Storage at High Temperature

Although work has been done to understand the sintering behavior and properties of Municipal Waste Incinerator Bottom Ashes to produce sintered (Bethanis et al. in Ceram Int 28:881–886, 2002; Cheeseman et al. in Resour Conserv Recycl 43:147–162, 2005; Bourtsalas et al. in Waste Manag 45:217–225, 2014; Taurino et al. in J Eur. Ceram Soc 37:323–331, 2017) or sinter-crystallized (Schabbach et al. in J Non Cryst Solids 357:10–17, 2011; Barbieri et al. in J Non Cryst Solids 354:521–528, 2008) ceramics, most of the trials reported in the literature focuses on the use of extensively milled bottom ashes powders (particle size around 1–50 µm), using processes that might not be easily transferable to industrial production at reasonable cost, and producing small cylinders with uniaxial compression technique on powders. This paper summarizes the development process of an extruded ceramic material made of gross-milled bottom ashes and waste clay, designed to be easily mass-produced using production capacities available in the building bricks industry, to be used as a high-temperature thermal energy storage material, which represents an alternative to the petrurgic ceramic previously developed for this application (Py et al. in J Sol Energy Eng 133:031008, 2011; Kere et al. in Int Conf Eng Waste Biomass Valoris, Porto, 2012; Py et al. in Stockage de l’ energie: energie thermique, stockage thermique haute temperature). Post-treated incinerator bottom ashes from a commercial incinerator has been collected, characterized and processed to form ceramic materials, using clay as a binder. Ashes were milled, dried, and mixed with various amounts of an illitic clay (produced as washing mud by a quartz quarry) prior to extrusion (cylindrical pellet) and firing at different temperatures, ranging from 1100 to 1120 °C. The sintered samples have been characterized in terms of density, mechanical strength, thermal capacity and thermal conductivity. Their mineral structure has also been studied. This work follows a study on the feasibility about the production of MWIBA based slabs with uniaxial compaction, and can be seen as an improvement regarding the shaping of the green bodies, more compatible with thermocline thermal energy storage process. The resulting sintered ceramics exhibit interesting properties such as relatively high mechanical resistance and low thermal conductivity, along with moderate density. These properties allow envisioning the use as filler material for thermocline thermal storage systems, especially considering the simplicity of the production process, relying on dry gross milling (jaw-mill), and firing at a temperature reachable within the building bricks and tiles industry. Production of adequate pieces to be used as thermal storage media seems however more relevant, the small size limiting the impact of sintering heterogeneities (formation of black bodies due to high content in fluxing agents like sodium and potassium).

Development and Application of Tube End Forming Process with Combined Swaging and Local Differential Pre-Heating

The performed research helped to develop and implement a new process of manufacturing small high pressure cylinders, in which the operation of pressing of tubular blanks with preliminary induction heating of the deformation zone. A two-layer inductor was designed and an industrial unit for preliminary differentiated induction pre-heating for the developed technological process. The forming rate was determined, ensuring preservation of the specified temperature difference and manufacturing of deformed tube end in accordance with the requirements for its geometry. Heating die-blocks were designed for blanks deforming for application in manufacturing of diameter, allowing keeping the necessary temperature gradient at deforming. Developed technological lubricants can be used for obtaining high quality products, increase in labor protection and die-blocks durability.

A Study on In-Cylinder Flow of Small Engine Using Steady-State Flow Benches

In-cylinder air flow structures are known to strongly impact on the performance and combustion of internal combustion engines (ICE). Therefore, the aim of this paper is to experimentally study an IC engine in-cylinder flow under steady-state conditions. Steady-state flow bench methods can be used to characterize the in-cylinder flow engine. The experiments were carried out on the small cylinder head with pressure difference across the inlet valves of 100 to 300 mmH2O. The experimental results are presented in terms of the measured air flow rate, flow coefficient and discharge coefficient. Moreover, the CFD used to illustrate the evolution of tumble motion in-cylinder engine. The results show that air volume flow rate and flow coefficient increased as the valve lift increases but the coefficient of discharge decrease if valve lift increase. The higher the pressure drop the higher the mass flow rate value. However, the higher the pressure drop the lower the value of flow coefficient and discharge coefficient.

DRAG INVESTIGATION AROUND A CYLINDER AND SYMMETRIC AIRFOIL IN TANDEM WITH DIFFERENT GAPS AND ANGLES OF ATTACK

A Numerical simulation for the turbulent airflow around a symmetrical airfoil (NACA 0012) adjusted in tandem with circular cylinder, the airfoil were adjusted at variable angle of attack between (5-20°) with positive clockwise inclination setting the cylinder center in front of the leading-edge centroid using the realizable K-ɛ turbulent model in the ANSYS FLUENT 17 package is performed. The effect of changing the adjusted tandem bodies’ configuration, gap (0.05-0.1) and the cylinder size variation on the flow pressure distribution and the airfoil drag coefficient were investigated. The simulation considered in free stream uniform velocity of (25 m/sec) at standard atmospheric pressure. The results showed that using a cylinder with diameter equal to leading edge diameter causes more pressure drop as the tandem gap decreased, noticing that this effect becomes more significant at a high angle of attack. A valuable reduction in drag coefficient of this configuration is achieved and it becomes more with a smaller cylinder diameter with respect to gap distance.

Accumulation of heavy particles in circular bounded vortex flows induced by two small rotating cylinders

In the present study, we adopt an Eulerian–Lagrangian CFD model based on the discrete element method (DEM) and immersed boundary method (IBM) to numerically investigate the accumulation behavior of heavy particles in circular bounded vortex flows induced by two small rotating cylinders. Both one-way and two-way couplings combined with the particle-particle and particle-wall collisions which are resolved by a hard-sphere approach are analyzed and effects of Stokes number, Reynolds number, the center-to-center distance between the circular domain and each small cylinder (r1) and particle number are also comprehensively explored. It is found that, under one-way coupling, there is always a stable state for the accumulation of particles trapped inside the circular domain. Moreover, five different particle accumulation patterns are identified as the two small rotating cylinders move away from the domain center and the critical values of r1 are also reported. However, under two-way coupling, the motion of the particles is irregular and the stable closed trajectories or accumulation points appearing in cases under one-way coupling cease to exist, due to the intense interaction between particles and the gas phase. In addition, many more particles accumulate on the wall under two-way coupling than under one-way coupling at the same conditions, demonstrating that the influence of particles on the flow will in turn strongly affect the particle motion and push more particles to the wall. The percentage of particles accumulated on the wall increases with increasing Stokes number and Reynolds number, whereas it decreases as the center-to-center distance between the circular domain and each small rotating cylinder increases under both one-way and two-way couplings.

Behavioural effect of continuous Theta Burst Stimulation in macaque parietal cortex

Event Abstract Back to Event Behavioural effect of continuous Theta Burst Stimulation in macaque parietal cortex Lara Merken1, Maria C. Romero1, 2*, Peter Janssen1 and Marco Davare2 1 Laboratory for Neuro- and Psychophysiology, Doctoral School of Biomedical Sciences, KU Leuven, Belgium 2 Movement Control and Neuroplasticity Research Group, Department of Kinesiology, Biomedical Sciences Group, KU Leuven, Belgium Theta-burst stimulation (TBS), a well-known type of repetitive Transcranial Magnetic Stimulation (TMS), is a powerful neuromodulation tool due to its ability to induce long-term changes in brain activity. However, behavioural results in human volunteers are still highly variable. Recently, Romero et al. (FENS Forum of Neuroscience Berlin, 2018; Abstract No. D037) showed that continuous TBS (cTBS; triplets of pulses at 50 Hz, applied every 200 ms, during 20 sec) induces a robust reduction in neuronal excitability of parietal neurons in rhesus monkeys. Here, we studied the effect of cTBS on the macaque parietal cortex, by measuring the grasping times (GT) during a visually-guided grasping (VGG) task. Monkeys were trained to perform the VGG under six different conditions, combining the grasping of two objects (large and small cylinder, i.e. power grip and precision grip, respectively) under three different stimulation conditions: no stimulation (NS), low stimulation (LS) - 40% of the resting motor threshold (rMT) -, and high stimulation (HS) - 80% of the rMT -. Data were obtained from two rhesus monkeys (3 sessions per condition, average of 797 trials/session in monkey 1 and 862 trials/session in monkey 2). cTBS induced significant changes (p < 0.05 two-tailed) in GT in both monkeys. In the power grip sessions of monkey 1, high stimulation cTBS significantly increased the GT from 20 min to at least 120 min post-cTBS by up to 20% compared to NS (p < 0.001, two-tailed). In contrast, for precision grip, cTBS caused a significant reduction in the GT after 100 min to at least 120 min post-cTBS (5% reduction compared to NS, p < 0.001, two-tailed). For monkey 2, we also observed opposite effects for both objects. For power grip, the GT was significantly reduced from 20 min to at least 120 min post cTBS (max of 12% reduction compared to NS, p < 0.05 two-tailed), while for precision grip cTBS significantly increased the GT from 80 min post cTBS to at least 120 min (up to 11% increase compared to NS, p < 0.05, two-tailed). Interestingly, in each condition and in each monkey, low stimulation cTBS increased or decreased the GT in the opposite direction compared to the effect of high stimulation. A two-way ANOVA for grip type (power/precision grip) and stimulation type (high/low/no) as factors, showed significant interactions for all tested time intervals in both monkeys (p < 0.01). These findings demonstrate long-lasting changes of cTBS on behaviour, which are strongly dependent on the applied stimulation intensity. Keywords: TMS, transcranial magnetic stimulation, Theta-burst stimulation (TBS), Visually-guided grasping, Power grip, macaque, Precision Grip Conference: 13th National Congress of the Belgian Society for Neuroscience , Brussels, Belgium, 24 May - 24 May, 2019. Presentation Type: Poster presentation Topic: Behavioral/Systems Neuroscience Citation: Merken L, Romero MC, Janssen P and Davare M (2019). Behavioural effect of continuous Theta Burst Stimulation in macaque parietal cortex. Front. Neurosci. Conference Abstract: 13th National Congress of the Belgian Society for Neuroscience . doi: 10.3389/conf.fnins.2019.96.00075 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 23 Apr 2019; Published Online: 27 Sep 2019. * Correspondence: PhD. Maria C Romero, Laboratory for Neuro- and Psychophysiology, Doctoral School of Biomedical Sciences, KU Leuven, Leuven, Belgium, mela.romero@kuleuven.be Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Lara Merken Maria C Romero Peter Janssen Marco Davare Google Lara Merken Maria C Romero Peter Janssen Marco Davare Google Scholar Lara Merken Maria C Romero Peter Janssen Marco Davare PubMed Lara Merken Maria C Romero Peter Janssen Marco Davare Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Investigating the Effects of Interaction of Single-Tine and Rotating-Tine Mechanisms with Soil on Weeding Performance Using Simulated Weeds

Abstract. Mechanical weeding augmented with automation technology should result in highly effective weeding systems. However, the interaction between weeding mechanisms and soil is not well understood. Moreover, soil is highly variable, which makes studying this interaction challenging. The main objective of this research was to develop a method to investigate the effects of mechanical tool-soil interaction on weeding performance for different operating conditions in a controlled environment. Experiments were conducted in an indoor soil bin with loam soil, and the weeding performance was studied using small wooden cylinders as simulated weed plants. The investigations featured a single cylindrical tine and a rotating tine mechanism, vertically oriented and inserted into the soil. The total width of soil disturbance and potential weeding rate were evaluated for the single cylindrical tine at different levels of three operating parameters: tine diameter (6.35, 7.94, and 9.53 mm), working soil depth (25.4, 50.8, and 76.2 mm), and tine speed (0.23 and 0.45 m s-1). Potential weeding rate was examined for the rotating tine mechanism with two operating parameters: working soil depth (25.4 and 76.2 mm) and rotational speed (25, 50, and 100 rpm). Statistical analysis was performed using ANOVA at p &amp;lt; 0.05. A simulation of the rotating tine mechanism was developed that estimated the disturbed area. For the single tine, soil disturbance width was independent of tine speed; however, tine diameter and depth had significant effects, as the width increased with increased levels of these two parameters. All three parameters had significant effects on the potential weeding rate of the single tine, and the rates were observed to increase with higher levels of the parameters. For the rotating tine mechanism, both depth and rotational speed were significant. The potential weeding rate for the rotating tine mechanism was found to increase with higher levels of these parameters. The results showed that although the width of soil disturbance due to a cylindrical tine was affected by the tine diameter and working soil depth, operating parameters such as increased longitudinal and rotational speeds also affected plant disturbance. The percentage of disturbed soil area in the simulation followed similar patterns as the percentage of disturbed plants observed in the experiments. Keywords: Inter-row weeding, Intra-row weeding, Mechanical weeding, Rotating tine mechanism, Soil disturbance, Tine.

Turbulence generated by small cylinders tethered in a grid

Turbulence generated by small cylinders tethered in a grid

Thermal radiation modelling of pool fire with consideration on the nonuniform temperature in flame volume

The accidental leakages of combustible fuel during storage and transportation cause the pool fires which impose hazardous heat on the nearby occupants and facilities mainly by thermal radiation. This paper presents a new semi-empirical radiation model, namely, the multi-layer cylindrical flame model to predict the radiant heat flux field of pool fires. As the centerline temperature of pool fire varies significantly with vertical height, a formula is proposed to characterize the vertical profile of flame surface emissive power with which the new model can predict the radiant heat flux. The reasonable layer number (the number of small cylinders used for model prediction) can be determined using sensitivity analysis. Comparisons with the experimental data of methanol, heptane, toluene and propane pool fires of different pool diameters indicate that the new radiation model can give a good prediction on the thermal radiation in both horizontal and vertical directions, in spite of fuel type and pool diameter. In comparison with the point source model and three typically single cylindrical flame models, the new radiation model seems to give encouraging results relative to the validity of model system. Sensitivity analysis is also conducted to rank the importance of model parameters.

Effects of Connection Type between Surface Vessel and Submersible Propeller on Motion Performance of Wave Glider

Wave Glider is an autonomous surface vehicle that directly uses wave energy to generate forward power and has been widely used in marine survey and observation. Wave Glider is composed of surface vessel, submersible propeller and the connection structure between them. Connection types are thought to be related to the performance of Wave Glider closely. In this paper, the effects of the connection structure between the surface vessel and the submersible propeller on the motion performance of the Wave Glider are studied. Several connection types such as rigid rod, cable, multi-link chain and elastic rod are applied to connect the surface vessel and the submersible propeller. The models of connection structures are developed respectively. Among them, cable model is established with a finite number of small cylinders, which connected by spring and damping elements; multi-link chain can be seen as hinged by multiple rigid rods; elastic rod model can be looked on as several segments linked with elastic components. Considering the connection characteristics, the integrated dynamic models are established by applying multi-body dynamics software ADAMS (Automatic Dynamic Analysis of Mechanical Systems) with consideration of the hydrodynamic forces on different components of Wave Glider. The propulsion performance of the Wave Glider is calculated by using numerical method, and the simulation results showed that the difference of propulsion performance with different connection types of the Wave Glider is slightly. But serious impacts can occur on the connections of rigid rod and multi-link chain. They can lead to serious extra load on the structure of Wave Glider. From the engineering practice of Wave Glider application, the cable connection is more convenient to transport, deploy, recover and store. It is also the generous connection type for wave glider.

Suppression of fluctuating lift on a cylinder via evolutionary algorithms: Control with interfering small cylinder

A generalized model-free method to optimize parameters for open-loop and closed-loop control in fluid mechanics applications is presented. A multi-objective evolutionary algorithm (MOEA) is employed to minimize the oscillating lift caused by vortex shedding from a cylinder of diameter D via the insertion of a secondary control cylinder of diameter D/8. The first objective of the algorithm is to minimize the fluctuating force coefficient CLRMS, while the second objective is to minimize the actuation power required to drive the control cylinder. Experiments are carried out in a free surface water channel at ReD = 12 500 and verified for robustness to changes in Reynolds number at ReD = 17 000. The control cylinder is prescribed a position as well as a periodic sinusoidal motion in two dimensions. The MOEA efficiently handles the larger optimization parameter space, with the final solution suppressing CLRMS by over 90% using near-zero actuation power. Further, the MOEA inherently provides a sensitivity study as to the influence of the different parameters and also in which spatial area the greatest influence is expressed. The dynamics of the optimal suppression case are compared to those of the baseline case (no control cylinder) using phase averaged and mean particle image velocimetry and direct force measurements.

A model for surface tension in the meshless finite volume particle method without spurious velocity

A surface tension model has been developed in the finite volume particle method (FVPM). FVPM is a conservative, consistent, meshless particle method that incorporates properties of both smoothed particle hydrodynamics and the mesh-based finite volume method. Surface tension force is applied only on free-surface particles, which are inexpensively and robustly detected using the FVPM definition of interparticle area, analogous to cell face area in the finite volume method. We present a model in which the direction of the pairwise surface tension force is approximated by the common tangent of free-surface particle supports. The new surface tension model is implemented in 2D. The method is validated for formation of an equilibrium viscous drop from square and elliptical initial states, drops on hydrophobic and hydrophilic walls, droplet collision, and impact of a small cylinder on a liquid surface. Results are practically free from parasitic current associated with inaccurate curvature determination in some methods.

Functional differences in upper limb movement after early and chronic stroke based on kinematic motion indicators.

The main purpose of this study was to determine the changes in kinematic parameters of ischemic stroke affected upper limbs, during simple functional activity, to determine the most relevant changes. The OptiTrack system was used for motion capture. To determine upper extremity function in Activities of Daily Living (ADL) tasks. During particular phases, the following matrices were chosen: mean and peak speed, normalized movement unit, normalized jerk and phase movement time. The chosen matrices represent the speed and smoothness profile of end-point data. The the arm-trunk compensation was also taken into consideration. Twenty stroke patients, in early (G1 from 1 to 3 months after stroke) and chronic stage (G2 from 6 months to 1 year), were studied. The large and small cylinder forward and back transporting phases were evaluated. The most significant differences between groups G1 and G2 were in mean and peak speed of the forward transport of the large and small cylinders for the paretic limb. Significant differences were also found for the smoothness (measured by movement unit, mean and peak speed and jerk) where the G2 group had a rougher motion. There were also differences in arm-trunk compensation in the frontal plane. The variables used in the study showed applicability in assessing kinematic parameters in both the early and chronic period after stroke.

Modification of turbulent wake characteristics by two small control cylinders at a subcritical Reynolds number

In this paper, the flow around a main circular cylinder with two small control cylinders is numerically investigated at a subcritical Reynolds number of 3900. Two small control cylinders with diameter ratio of d/D = 0.04 (d and D are the diameters of the control cylinders and the main cylinder, respectively) are symmetrically placed inside the separated shear layers emanating from the main cylinder. The computation is performed with highly resolved direct numerical simulations employing a high-order spectral/hp element method. For validation purposes, the results of the flow over a single cylinder are presented at first, and the current simulation is in good agreement with the existing experiments and large eddy simulations. For the main cylinder with the two control cylinders, the dynamics of shear layers is found to be modified strongly owing to the disturbance from the small control cylinders. As a consequence, the recirculation length is decreased by 89% as compared to that of a single cylinder. The presence of the small control cylinders further leads to a significant increase in the fluctuating lift and the mean drag exerting on the main cylinder. Furthermore, the statistical analysis and turbulent wake visualization imply that the turbulent intensity is amplified in the near wake region and becomes weaker further downstream. This study then suggests that the small control cylinders located in the near wake region of the main cylinder may work differently in the turbulent wake against that in the laminar wake.

Defect nucleation modelling

The purpose of this article is to compare concepts of defect nucleation based on bifurcation of equilibrium solution and on damage modelling. The nucleation criterion is defined as a bifurcation of the equilibrium solutions of the perfect body and of the imperfect one when the size of the defect vanishes. The defect is considered as a small volume which evolves as a damaged zone. To study the influence of geometry of the defect on the critical loading governing its initiation, we consider the particular cases of a linear elastic composite sphere and of a linear elastic composite cylinder, for which the equilibrium solutions are known when the radial distribution of elastic bulk modulus is given simultaneously with a uniform shear modulus. The initial defect is a small sphere or a small cylinder, respectively, it can be a cavity or a kernel made with an elastic material with lower mechanical properties.

Modeling of capillary-driven flows in axisymmetric geometries

We present an analytical approach, as well as computer simulations based on the free surface lattice-Boltzmann (FSLB) method, in order to model capillary-driven infiltration of liquids into porous structures. The analytical method is an extension of the Lucas-Washburn (LW) equation and applies to axisymmetric geometries with a circular cross-section. The treatment of irregular capillaries is achieved by a discretization procedure in which the original geometry is divided into small cylinders. In order to validate the derived analytical equation, we perform FSLB simulations in test geometries which show a good agreement.

The meniscus on the outside of a circular cylinder: From microscopic to macroscopic scales

We systematically study the meniscus on the outside of a small circular cylinder vertically immersed in a liquid bath in a cylindrical container that is coaxial with the cylinder. The cylinder has a radius R much smaller than the capillary length, κ-1, and the container radius, L, is varied from a small value comparable to R to ∞. In the limit of L≪κ-1, we analytically solve the general Young-Laplace equation governing the meniscus profile and show that the meniscus height, Δh, scales approximately with Rln(L/R). In the opposite limit where L≫κ-1,Δh becomes independent of L and scales with Rln(κ-1/R). We implement a numerical scheme to solve the general Young-Laplace equation for an arbitrary L and demonstrate the crossover of the meniscus profile between these two limits. The crossover region has been determined to be roughly 0.4κ-1≲L≲4κ-1. An approximate analytical expression has been found for Δh, enabling its accurate prediction at any values of L that ranges from microscopic to macroscopic scales.

Critical condition of inner cylinder radius for sustaining rotating detonation waves in rotating detonation engine thruster

We describe the critical condition necessary for the inner cylinder radius of a rotating detonation engine (RDE) used for in-space rocket propulsion to sustain adequate thruster performance. Using gaseous C2H4 and O2 as the propellant, we measured thrust and impulse of the RDE experimentally, varying in the inner cylinder radius ri from 31 mm (typical annular configuration) to 0 (no-inner-cylinder configuration), while keeping the outer cylinder radius (ro = 39 mm) and propellant injector position (rinj = 35 mm) constant. In the experiments, we also performed high-speed imaging of self-luminescence in the combustion chamber and engine plume. In the case of relatively large inner cylinder radii (ri = 23 and 31 mm), rotating detonation waves in the combustion chamber attached to the inner cylinder surface, whereas for relatively small inner cylinder radii (ri = 0, 9, and 15 mm), rotating detonation waves were observed to detach from the inner cylinder surface. In these small inner radii cases, strong chemical luminescence was observed in the plume, probably due to the existence of soot. On the other hand, for cases where ri = 15, 23, and 31 mm, the specific impulses were greater than 80% of the ideal value at correct expansion. Meanwhile, for cases ri = 0 and 9 mm, the specific impulses were below 80% of the ideal expansion value. This was considered to be due to the imperfect detonation combustion (deflagration combustion) observed in small inner cylinder radius cases. Our results suggest that in our experimental conditions, ri = 15 mm was close to the critical condition for sustaining rotating detonation in a suitable state for efficient thrust generation. This condition in the inner cylinder radius corresponds to a condition in the reduced unburned layer height of 4.5–6.5.

Force distribution of a cylindrical grip differs between dominant and nondominant hand in healthy subjects.

Grip strength and load distribution of the hand are important parameters for evaluating hand function. The purpose of this study was to analyze and compare grip force and load distribution of dominant and nondominant hands in right-handed healthy subjects. Gripping measurements were performed on 40 healthy right-handed subjects using a cylindrical gripping device. Two different cylinders with circumferences of 150mm (small cylinder)and 200mm (large cylinder), respectively, were used for the measurements. Subjects were assigned to either the small or the large cylinder with respectto their hand size.Maximum and mean force applied during three intervals of gripping as well as the percent contribution of each digit, thenar, and hypothenar in relation to the total load applied were acquired. Values of dominant and nondominant hands were compared. Percent contribution of mean grip strength differed for the thumb (p = 0.007), ring finger (p < 0.001), little finger (p = 0.047), and palm (p < 0.001). Comparing the dominant and nondominant side, the dominant hand showed a lower contribution of the thumb, ring finger, and little finger, but a higher contribution of the palm. When analyzing maximum grip, percent contribution of the small fingers was equal between dominant and nondominant side (p = 0.1). Differences between dominant and nondominant thumb, ring finger, and palm persisted (p = 0.007, p = 0.001, p = 0.005, respectively). No differences could be shown for the index finger, middle finger, thenar, and hypothenar when analyzing both mean and maximum force. Percent contribution of the thumb and the fingers to total grip strength differed between dominant and nondominant hands with a change in distribution when assessing maximum grip force. In right-handed subjects, thumb and ring finger have important roles during gripping.