Diagonal Modes Research Articles

Stereoscopic cells of three-dimensional detonation waves propagating in square ducts

The present study delves into the examination of the stereoscopic cells and wavefront structures characterizing the propagation of three-dimensional detonation waves within square ducts. Leveraging numerical solutions derived from three-dimensional reactive Euler equations, incorporating an induction-exothermic reaction kinetic model, this work reveals the distinct classification of three modes of detonation waves based on the direction of propagation and the phase characteristics of transverse shock waves on the wavefront. This paper delineates the presence of two different types of phenomena: duct wall slapping waves due to shock–wall collisions and internal slapping waves resulting from shock interactions. Furthermore, this investigation exposes the existence of two distinct types of triple-wave lines on the wavefront: the first comprising a strong Mach disk, a weak Mach disk, and a transverse shock wave; the second characterized by a weak Mach disk, an incident shock wave, and a transverse shock wave. Notably, the pressure behind the first type of triple-wave line is observed to be the highest. It elucidates the transition from two- to three-dimensional detonation waves, revealing that the prevalence of transverse shock waves on the wavefront in the rectangular and diagonal modes is twofold and quadruple, respectively, when compared to their two-dimensional counterparts within identical ducts/channels.

Transmissible topological edge states based on Su–Schrieffer–Heeger photonic crystals with defect cavities

Abstract Topological photonic crystals have great potential in the application of on-chip integrated optical communication devices. Here, we successfully construct the on-chip transmissible topological edge states using one-dimensional Su–Schrieffer–Heeger (SSH) photonic crystals with defect cavities on silicon-on-insulator slab. Different coupling strengths between the lateral modes and diagonal modes in photonic crystal defect cavities are used to construct the SSH model. Furthermore, two photonic SSH-cavity configurations, called α and β configurations, are designed to demonstrate the topological edge states. Leveraging the capabilities of photonic crystal transverse electric modes with on-chip transmission, we introduced a waveguide to excite a boundary defect cavity and found that the transmission peak of light, corresponding to the topological edge state, can be received in another boundary defect cavity, which is caused by the tunnel effect. Moreover, the position of this peak experiences a blue shift as the defect cavity size increases. Therefore, by tuning the size of the SSH defect cavity, on-chip wavelength division multiplexing function can be achieved, which is demonstrated in experiments. The ultrafast response time of one operation can be less than 20 fs. This work harmonizes the simplicity of one-dimensional SSH model with the transmissibility of two-dimensional photonic crystals, realizing transmissible on-chip zero-dimensional topological edge states. Since transmission peaks are highly sensitive to defect cavity size, this configuration can also serve as a wavelength sensor and a reconfigurable optical device, which is of substantial practical value to on-chip applications of topological photonics.

Development of a hybrid intelligent switching hydraulically interconnected suspension system under a multi-objective optimized mode selection strategy with real-world condition

Reduction in vertical acceleration is crucial for car manufacturers. This parameter evaluates the comfort index. Moreover, the handling index is another feature that must be under investigation. The suspension system has an essential impact on these two indices. A hybrid intelligent switching hydraulically interconnected suspension (HISHIS) is proposed. The parallel configuration is combined with the diagonal configuration in the suspension system. A mode selection strategy is discussed to select the layout between diagonal and parallel configurations. The only mode of parallel configuration is called Anti-pitch configuration. The diagonal configuration has three modes, including Anti-roll, Anti-oversteering, and Anti-vibration configuration. According to the mode selection strategy, one of these three diagonal configuration modes might be selected. The origin of roll and pitch generation is inertia force and road inputs. Hopfield neural network can recognize the origin of roll and pitch generation. Therefore, the performance of valves will change according to Hopfield neural network recognition. The results of different maneuvers show the improvement at each targeted parameter in various tasks independently. The data logger gathered the acceleration of the vehicle in real-world conditions. However, the margins of the selection strategy block are multi-objective optimized with a genetic algorithm to reach better responses in real-world conditions. The roll angle, yaw rate, allowable exposure time, and pitch angle are improved by 63%, 5%, 40%, and 99% on average. Also, optimizing the selection strategy improves the allowable exposure time by 9%. Obviously, by combining two layouts, it is possible to have a flexible situation to improve ride comfort and handling situations. In addition, there is a conditional strategy to select different layouts and modes to reach a better response.

Quasi-static experimental study on seismic performance of exterior shear key with different failure modes

The shear key with horizontal failure mode manifests secondary stiffness-strengthening capacity comparing to the diagonal and slide shear modes. It is more suitable for protecting bridges that sustain multiple hazard actions. However, the seismic performance of shear keys with horizontal failure mode has seldom been addressed. This study designed and manufactured ten RC exterior shear key models involving 1:3 geometrical scaling to achieve three failure modes with specific reinforcement layouts. A quasi-static experiment was performed to investigate the seismic performance of shear keys, including crack observation, force–displacement relationship, rotation and stress distribution characteristics. The experiment results indicate that the failure mode depends on the proportion of reinforcement capacity, and can affect the maximum resistance of shear keys. The shear key with horizontal failure exhibits apparent secondary stiffness strengthening characteristics, whereas the diagonal and sliding failure modes suffer persistent reduction under large deformations. Furthermore, the diagonal shear key exhibits the highest residual capacity under severe damage. The measured data are compared with the existing analytical models in terms of both peak capacity and envelope curves, showing the models are more applicable to diagonal failure shear key than the others.

Laser Powder Bed Fusion-built Ti6Al4V Bone Scaffolds Composed of Sheet and Strut-based Porous Structures: Morphology, Mechanical Properties, and Biocompatibility

Laser powder bed fusion (L-PBF)-built triply periodic minimal surface (TPMS) structures are designed by implicit functions and are endowed with superior characteristics, such as adjustable mechanical properties and light-weight features for bone repairing; thus, they are considered as potential candidates for bone scaffolds. Unfortunately, previous studies have mainly focused on different TPMS structures. The fundamental understanding of the differences between strut and sheet-based structures remains exclusive, where both were designed by one formula. This consequently hinders their practical applications. Herein, we compared the morphology, mechanical properties, and biocompatibility of sheet and strut-based structures. In particular, the different properties and in vivo bone repair effects of the two structures are uncovered. First, the morphology characteristics demonstrate that the manufacturing errors of sheet-based structures with diverse porosities are comparable, and semi-melting powders as well as the ball phenomenon are observed; in comparison, strut-based samples exhibit cracks and thickness shrinking. Second, the mechanical properties indicate that the sheet-based structures have a greater elastic modulus, energy absorption, and better repeatability compared to strut-based structures. Furthermore, layer-by-layer fracturing and diagonal shear failure modes are observed in strut-based and sheet-based structures, respectively. The in vivo experiment demonstrates enhanced bone tissues in the strut-based scaffold. This study significantly enriches our understanding of TPMS structures and provides significant insights in the design of bone scaffolds under various bone damaging conditions.

Numerical study of coupled slosh modes in a 3D vessel subjected to multi-directional excitations

Present study explores liquid sloshing in a three-dimensional (3D) rectangular tank subjected to surge and coupled surge, sway and heave excitations. A number of applications of practical interest in nuclear systems such as, spent fuel storage tanks, fast reactor vessels, pool type coolant etc will be benefited from such analysis. Effect of harmonic excitation is investigated emphasizing finite liquid depth when the internal resonance condition 1:1 is satisfied between the natural frequencies of dominant modes (1,0), (0,1) and (0,2). The numerical model was validated against available in–house experimental shake table studies. Temporal snapshots of velocity magnitudes and free surface time history at different locations are presented when the tank is excited under two different loading conditions. The amplification of diagonal slosh modes were observed under planar excitation. This analysis assumes significance, as the attendant hydrodynamic forces could eventually cause fatigue failure of the tank structure. Non-linear square-like, swirling and wave breaking features were observed, when the tank was subjected to earthquake excitation.

Probability-Based Fast Intra Prediction Algorithm for Spatial SHVC

Due to multi-layer encoding and Inter-layer prediction, Scalable High Efficiency Video Coding (SHVC) has extremely high coding complexity. It is very crucial to improve its coding speed so as to promote widespread and cost-effective SHVC applications. In this paper, we propose a new probability-based fast Intra prediction algorithm for spatial SHVC. More specifically, first, we integrate depth probabilities with textural based all-zero blocks and all-nonzero blocks through Lagrange Interpolation Polynomial (LIP) to derive thresholds to early skip unlikely depths and early terminate depth selection. Second, to early skip Intra mode prediction, we combine mode probabilities with Jarque-Bera test through LIP to test the residual coefficients of Inter-layer reference (ILR) mode. Third, we adopt the difference of Hadamard Costs (HCs) of horizontal, vertical and diagonal directional modes to predict candidate directional modes (DMs), and then exploit both the percentages of gradient amplitudes and HCs for DM early termination. Experimental results demonstrate that the proposed algorithm can achieve a speed up gain of more than 61% with 0.03% decrease in Bjøntegaard Delta Bit Rate on average.

Analytical and Experimental Study of the Piles Cap Normal and Light Weight Aerated Concrete: Literature Review

The main objective of this study is to understand the work of the pile caps made of lightweight aerated foam concrete and study the many factors affecting the ability and the capacity of the shear. The study was done by analyzing previous practical and theoretical experiences on the reinforced concrete pile caps. The previous practical results indicated that all specimens failed by shear diagonal compression or tension modes except one specimen that failed flexural-shear mode. Based on test specimens' practical results and behavior, some theoretical methods for estimating the ultimate strength of reinforced concrete pile caps have been recommended, some of which evolved into the design documents available on the subject. A theoretical and practical study of compression concluded that the shear capacity is limited by the nodal zone bearing stresses. The flexural capacity can be described by the column load that would cause the yielding of the tie (i.e., steel reinforcement). Therefore, the design of pile caps should include a check on bearing strength to be added to the traditional section force approach for pile cap design.

SIMILAR MATERIALS FOR QUASI-STATIC SCALED TESTS OF FAULT-CROSSING TUNNELS

The design of similar materials is one of the key links to ensure the matching of the physic-mechanical properties between the prototype and the test specimens. Based on the prototype of the Xianglu mountain tunnel of the water diversion project in the central Yunnan province, China, the scaling relationship of the physical quantities in the quasi-static scaled test of a fault-crossing tunnel is derived in this study according to the similarity theory and dimensional analyses. The similar materials of concrete and rock mass used in the test are developed with barite powder and sand as the aggregates and with gypsum and lime as the cementing material. The effects of each component on the physic-mechanical properties of the similar materials are investigated through orthogonal tests. The test results indicate that the strength, elasticity modulus and density of the similar materials can be significantly changed by the overall content of the high-strength gypsum and water-gypsum ratio. Small variation of the strength of the similar material is found when the sand-gypsum ratio is between 0.8 and 1.2, but the strength significantly decreases when the sand-gypsum ratio is between 3 and 12. The elastoplastic performance and the brittle failure mode of Grade C30 concrete can be well simulated by the similar material made of high strength gypsum, low strength gypsum, barite powder and sand. The tensile splitting and the diagonal shear failure modes of rock mass of Grade IV and V can be well simulated by the proposed similar material made of high strength gypsum, lime and sand. The development process and ratios of similar materials can provide important reference for model test and numerical simulation.

Novel Dual band SIW Filter Using Quad mode Cavity

A dual-band bandpass substrate integrated waveguide (SIW) filter is proposed using a quad-mode cavity in this paper. First two degenerative modes (TE102 and TE201) with via perturbation give the first passband. The second passband is realised by using higher modes (side and diagonal modes of TE202) which are obtained by putting square slot at the center of the cavity. The square slot increases the frequency ratio of the center frequencies of first and second passbands. Moreover, orthogonal feed-lines are used in the proposed design to increase transmission zeros (TZs) which helps to improve the selectivity and out-of-band rejection of the filter. Designed and fabricated a dualband filter prototype using a single layer printed circuit board (PCB) technology, size is only 19 mm × 19 mm. The insertion losses are 2.1 dB and 2.4 dB, and fractional bandwidths of 3.40 per cent and 2.00 per cent at 11.00 and 15.58 GHz, respectively. The measurement results show close agreement with the simulation results.

A Differential Dual-Polarized SIW Cavity-Backed Slot Antenna

A compact, low-profile, and dual-polarized differential slot antenna with high isolation and high common-mode rejection is presented in this communication. The antenna is composed of a cross-shaped slot backed by a square substrate integrated waveguide (SIW) cavity. The two differential pairs of grounded coplanar waveguide are used for the excitation of the differential signals. These differential signals excite the diagonal TE120 and TE210 modes of the SIW cavity. The proposed antenna offers a differential gain of 7.4 dBi with a front-to-back ratio of 22 dB. A prototype of the designed differential antenna is fabricated as a proof of concept. The experimental results show that the proposed antenna is a good candidate for various ${X}$ -band applications.

Compact Dual-Band Balanced SIW Bandpass Filter With Improved Common-Mode Suppression

The contribution of this letter is to propose a novel substrate integrated waveguide (SIW) dual-band balanced bandpass filter (BPF), which exhibits characteristics of compact size and improved common-mode (CM) suppression. Two diagonal resonant modes TE102 and TE302 in a square SIW resonator with symmetric field distributions provide the possibility to realize balanced inputs/outputs, dual-passband responses and the vertically stacked structure for compact size. Without affecting the differential-mode (DM) responses, a novel method of using slotlines etched on one broadside of either SIW resonators to shift the resonant frequency of CM away from the DM passband is also proposed, to realize a higher CM rejection for this BPF. Meanwhile, perturbation vias have been utilized to adjust the center frequency of the lower passband, while the higher passband can remain almost unchanged. A second-order prototype is designed for the demonstration. Good agreement between simulation and measurement has been observed in the measurement.

Investigations of the CLOCK and BMAL1 Proteins Binding to DNA: A Molecular Dynamics Simulation Study.

The circadian locomotor output cycles kaput (CLOCK), and brain and muscle ARNT-like 1 (BMAL1) proteins are important transcriptional factors of the endogenous circadian clock. The CLOCK and BMAL1 proteins can regulate the transcription-translation activities of the clock-related genes through the DNA binding. The hetero-/homo-dimerization and DNA combination of the CLOCK and BMAL1 proteins play a key role in the positive and negative transcriptional feedback processes. In the present work, we constructed a series of binary and ternary models for the bHLH/bHLH-PAS domains of the CLOCK and BMAL1 proteins, and the DNA molecule, and carried out molecular dynamics simulations, free energy calculations and conformational analysis to explore the interaction properties of the CLOCK and BMAL1 proteins with DNA. The results show that the bHLH domains of CLOCK and BMAL1 can favorably form the heterodimer of the bHLH domains of CLOCK and BMAL1 and the homodimer of the bHLH domains of BMAL1. And both dimers could respectively bind to DNA at its H1-H1 interface. The DNA bindings of the H1 helices in the hetero- and homo-bHLH dimers present the rectangular and diagonal binding modes, respectively. Due to the function of the α-helical forceps in these dimers, the tight gripping of the H1 helices to the major groove of DNA would cause the decrease of interactions at the H1-H2 interfaces in the CLOCK and BMAL1 proteins. The additional PAS domains in the CLOCK and BMAL1 proteins affect insignificantly the interactions of the CLOCK and BMAL1 proteins with the DNA molecule due to the flexible and long loop linkers located at the middle of the PAS and bHLH domains. The present work theoretically explains the interaction mechanisms of the bHLH domains of the CLOCK and BMAL1 proteins with DNA.

Numerical study of three-dimensional detonation structure transformations in a narrow square tube: from rectangular and diagonal modes into spinning modes

Three-dimensional (3-D) detonation structure transformations from rectangular and diagonal modes into spinning modes in a narrow square tube are investigated by high-resolution simulation. Numerical simulations are performed with a Riemann solver of the HLLC-type, new cell-based structured adaptive mesh refinement data structure, high-order, parallel adaptive mesh refinement reactive flow code. A simplified one-step kinetic reaction model is used to reveal the 3-D detonation structure. The four different types of initial disturbances applied in the ZND profiles lead to the structures of rectangular in phase, rectangular out of phase, rectangular partial out of phase and diagonal, respectively, during the initial stages of detonation propagation. Eventually, all these detonation structures evolve into the self-sustained spinning detonations. The asymmetric disturbance leads to a stable spinning detonation much faster than the rest. The important features in the formation of spinning detonation are revealed using a 3-D visualization, and a remarkable qualitative agreement with experimental and numerical results is obtained with respect to the transverse wave dynamics and detonation front structures. The transverse wave collisions produce the unburnt gas pockets and the energy to sustain the detonation front propagation and distortion. The periodic pressure oscillation of front plays a complex role as it shifts the reaction zone structure with an accompanying change in the driving energy of transition and the detonation parameters which result in the more distorted front and the unstable detonation. Eventually, the unstable distorted detonation evolves into a spinning detonation.

Numerical Simulation and Proper Orthogonal Decomposition of the Flow in a Counter-Flow T-Junction

Large eddy simulations (LES) of the turbulent mixing in a T-junction have been carried out with the spectral element code Nek5000 at two inlet velocity ratios. Numerical results have been compared with an available experiment. Proper orthogonal decomposition (POD) has then been used to identify the most energetic modes of turbulence for both the velocity and temperature fields. Since POD was also performed on the experiment particle image velocimetry (PIV) data, a further means of verification and validation was available. The structure of the numerical POD modes and the time histories of the projection of each mode on the velocity field offer additional insight into the physics of turbulence in T-junctions. In particular, in the case of identical inlet velocities (T-junction velocity ratio equal to 1.0) the dynamics appears to be richer than might be expected and additional diagonal modes are present.

Enhancement of resonant and non-resonant magnetoelectric coupling in multiferroic laminates with anisotropic piezoelectric properties

Giant transverse magnetoelectric voltage coefficients |α̃E| = 751 and 305 V/cmOe at two electromechanical antiresonance frequencies are found in the symmetric metglas/[011]-oriented 0.7Pb(Mg1/3Nb2/3)O3–0.3PbTiO3 crystal/metglas laminate. Unique torsional and diagonal vibration modes are identified to be responsible for those giant |α̃E| values. Moreover, α̃E is found to be anisotropic depending on the in-plane magnetic field directions, making the piezoelectrics with anisotropic planar piezoelectricity potentially useful base materials for multi-frequency, phase-sensitive magnetoelectric devices.

High resolution WENO simulation of 3D detonation waves

In this paper, we develop a three-dimensional parallel solver using the fifth order high-resolution weighted essentially non-oscillatory (WENO) finite difference scheme to perform extensive simulation for three-dimensional gaseous detonations. A careful study is conducted for the propagation modes of three-dimensional gaseous detonation wave-front structures in a long square duct. The numerical results indicate that, the instability of detonation, overdrive factor, transverse dimension and initial perturbation are the main factors that influence the appearance of spinning detonation. For unstable detonation with an overdrive factor f=1.0, with the duct width decreasing, the transverse modes tend to be the lower ones. When the duct width is sufficiently small, detonation propagation is coupled to the lowest transverse mode in order to sustain itself. There is a maximum duct width for the appearance of spinning detonation. When the duct width is smaller than this value, the unstable detonation propagates in a spinning mode. When the duct width is larger than this value, spinning detonation disappears. For highly unstable detonation with an overdrive factor f=1.2, the formation of the spinning detonation does not depend on the initial perturbation and it only depends on the high instability of detonation and channel dimension in the transverse directions. Both initial rectangular modes and initial diagonal modes can eventually evolve into spinning modes. For mildly unstable detonation with an overdrive factor f=1.6, it is easier for the initial diagonal mode to trigger the spinning mode than for the initial rectangular mode. The formation of spinning detonation thus not only depends on the high instability of detonation and channel dimension in the transverse directions, but also depends on the initial perturbation. For the stable detonation with an overdrive factor f=1.1, when the initial perturbation is in the transverse cosine mode, the front of the stable detonation has a rectangular structure and slapping waves appear on the walls. When the initial perturbation is in the symmetrical mode along the diagonals of the detonation front, the diagonal detonation is formed and the slapping waves on the walls disappear.

Three-Dimensional Parallel Simulation of Formation of Spinning Detonation in a Narrow Square Tube

Four different formation processes of spinning detonation in a narrow square tube are investigated by three-dimensional parallel simulations. High-resolution simulations are performed with a Riemann solver of the HLLC-type, high-order, parallel AMR reactive flow code. The simulations clearly show that the detonation structure transforms from rectangular and diagonal modes into spinning mode respectively during the propagation processes. Transverse wave dynamic and periodic oscillation of the front plays a significant role in the spinning detonations' formation.

How wide is the transition to deconfinement?

Pure SU(3) glue theories exhibit a deconfining phase transition at a nonzero temperature, Tc. Using lattice measurements of the pressure, we develop a simple matrix model to describe the transition region, when T > Tc. This model, which involves three parameters, is used to compute the behavior of the 't Hooft loop. There is a Higgs phase in this region, where off diagonal color modes are heavy, and diagonal modes are light. Lattice measurements of the latter suggests that the transition region is narrow, extending only to about 1.2 Tc. This is in stark contrast to lattice measurements of the renormalized Polyakov loop, which indicates a much wider width. The possible implications for the differences in heavy ion collisions between RHIC and the LHC are discussed.

Macrocycles with two exclusive hydrogen-bonding modes

A series of large, 44-membered macrocycles 7a– e were synthesized and characterized, which display two different diagonal binding modes. The unsubstituted macrocycle 7a strongly binds naphthalene-2,6-dicarboxylate through hydrogen bonds with the association constant ( K a ± 15%) of 4500 M −1 in 40% (v/v) CD 3CN/CDCl 3 at 23 ± 1 °C. Introduction of an electron-withdrawing substituent (Cl) at all four corners increases the binding affinity (22,000 M −1 for 7b), while that of an electron-donating substituent (pyrrolidinyl) greatly decreases it (150 M −1 for 7c). The same propensity has been observed with macrocycles 7d and 7e bearing different substituents at two diagonal corners, suggesting that the relative population of the binding modes would be modulated by controlling the electron density of the aromatic ring.