Asymmetric Triangle Research Articles

THD improvement of piezoelectric MEMS speakers by dual cantilever units with well-designed resonant frequencies

In this study, a piezoelectric MEMS (Micro-Electro-Mechanical-System) speaker with thoughtfully selected resonant frequencies of dual cantilever units is designed and implemented. Based on the lead zirconium titanate (PZT) thin film with superior piezoelectric coefficient, the cantilever diaphragm is designed through the modal analysis. In the 1.5 mm by 1.5 mm cantilever array, a high-frequency actuation unit with resonance of 13.1 kHz and a low-frequency actuation unit with resonance of 6.35 kHz constitute the proposed piezoelectric MEMS speaker. The boost of sound pressure level (SPL) due to the resonant mode of low-frequency actuation unit reduces the total harmonic distortion (THD) around the subharmonic frequency of high-frequency actuation unit. Meanwhile, the asymmetric triangle diaphragm reduces the maximum stress in the structure when operating at the resonant frequency, thereby mitigating the THD spikes resulting from the nonlinear structural behavior. In pressure-field measurements, the proposed design can reach SPL ≥ 70.0 dB from 2.7 kHz to 15.0 kHz with only 0.179 Vrms input. At the same time, THD remains below 3.0 % from 3.2 kHz to 20 kHz. The outstanding performance under larger input signal and bias voltage is also verified. Actuated by 0.354 Vrms and 2 VDC bias, the maximum SPL achieves 111.9 dB and the SPL is higher than 80.0 dB from 3.3 kHz to 14.1 kHz. Furthermore, THD is lower than 3.0 % from 1.0 kHz to 8.9 kHz. A promising solution of piezoelectric MEMS speaker for in-ear applications is demonstrated in this study.

Moscow-Havana Relations. Continuities of the Past in an Asymmetric Triangle

This article examines Moscow-Havana relations from the Russian Revolution in November 1917 to the present to inform debates on (1) continuities from history impacting contemporary Russian foreign policy; (2) the assumption that before the Cuban Revolution of 1959 Moscow suffered from ‘geographical fatalism’ concerning Latin America; (3) contemporary Moscow-Havana relations; and (4) asymmetrical triangles in international relations. A rigorous historical qualitative analysis of primary and secondary sources is used to examine the periods November 1917–January 1959, 1959–1991, and 1992 onwards. Both realism and constructivism are utilised throughout. Acting as a bridge between historical research and the study of international relations this article posits that in each period Moscow and Havana’s individual relationships with Washington were key to Moscow-Havana relations. Continuities from history for the contemporary relationship are to both the November 1917–January 1959 era and the 1959–1991 period. Consequently, since 1917 an asymmetrical triangle comprising Moscow, Havana, and Washington has principally existed. Aiding its originality this article postulates that a ‘stable marriage’ with the most powerful member of an asymmetrical triangle (Washington) being the ‘pariah’ can become the norm. This finding has resonance for global politics and the behaviour of regional superpowers within their respective region.

Design of miniaturized multi-band hybrid-mode microstrip patch antenna for wireless communication

This research presents a small, compact microstrip patch antenna of multi-band antenna. The multi-band antenna can be scaled to higher frequencies, making it possibly useful in 5G applications. The antenna is made up of asymmetric scalene triangles slots on the right side of the patch, which is provided by the reference patch antenna. The modes of antenna, patch and slots are excited to obtain four bands. The antenna design is 25×25×1.4 mm<sup>3</sup> resonant at 3.93 GHz, 4.25 GHz, 5.37 GHz, and 6.18 GHz. The simulated design shows a peak gain of 4.44 dB at 3.93 GHz, 5.63 dB at 4.25 GHz, 5.91 dB at 5.37 GHz and 5.2 dB at 6.18 GHz. The total efficiency at 3.93 GHz and 4.25 GHz is -1.152 dB and -0.5174 dB, at 5.37 GHz and 6.18 GHz shows a total efficiency of -0.535 dB and -0.566 dB. Finally, the antenna is fabricated and measured. A good agreement shown between measurements and fabrication in terms of return loss.

Zero-order free holographic optical tweezers.

Holographic optical tweezers (HOTs) use spatial light modulators (SLM) to modulate light beams, thereby enabling the dynamic control of optical trap arrays with complex intensity and phase distributions. This has provided exciting new opportunities for cell sorting, microstructure machining, and studying single molecules. However, the pixelated structure of the SLM will inevitably bring up the unmodulated zero-order diffraction possessing an unacceptably large fraction of the incident light beam power. This is harmful to optical trapping because of the bright, highly localized nature of the errant beam. In this paper and to address this issue, we construct a cost-effective, zero-order free HOTs apparatus, thanks to a homemade asymmetric triangle reflector and a digital lens. As there is no zero-order diffraction, the instrument performs excellently in generating complex light fields and manipulating particles.

Individual Variability Is More Important Than Analytical Methods When Calculating Relative Speed of Beverage Bioavailability.

Deuterium oxide (D2O) appearance in blood is a marker of fluid bioavailability. However, whether biomarker robustness (e.g.,relative fluid delivery speed) is consistent across analytical methods (e.g.,cavity ring-down spectroscopy) remains unclear. Fourteen men ingested fluid (6ml/kg body mass) containing 0.15g/kg D2O followed by 45min blood sampling. Plasma (D2O) was detected (n = 8) by the following: isotope-ratio mass spectrometry after vapor equilibration (IRMS-equilibrated water) or distillation (IRMS-plasma) and cavity ring-down spectroscopy. Two models calculated D2O halftime to peak (t1/2max): sigmoid curve fit versus asymmetric triangle (TRI). Background (D2O) differed (p < .001, η2 = .98) among IRMS-equilibrated water, IRMS-plasma, and cavity ring-down spectroscopy (152.2 ± 0.8, 147.2 ± 1.5, and 137.7 ± 2.2ppm), but did not influence (p > .05) D2O appearance (Δppm), time to peak, or t1/2max. Stratifying participants based on mean t1/2max (12min) into "slow" versus "fast" subgroups resulted in a 5.8min difference (p < .001, η2 = .73). Significant t1/2max model (p = .01, η2 = .44) and Model × Speed Subgroup interaction (p = .005, η2 = .50) effects were observed. Bias between TRI and sigmoid curve fit increased with t1/2max speed: no difference (p = .75) for fast (9.0min vs. 9.2min, respectively) but greater t1/2max (p = .001) with TRI for the slow subgroup (16.1min vs. 13.7min). Fluid bioavailability markers are less influenced by which laboratory method is used to measure D2O as compared with the individual variability effects that influence models for calculating t1/2max. Thus, TRI model may not be appropriate for individuals with slow fluid delivery speeds.

The structure of glasses M2O-B2O3 (М – Li, Na, K): Estimation of thermodynamic characteristics of alkali borates and physicochemical modeling

The paper presents results of structural calculations carried out on the alkali borate glasses using physicochemical modeling based on Gibbs energy minimisation. Standard heat capacity, entropy and enthalpy of formation values for lithium, sodium and potassium borates are estimated by regression analysis for use as the input data for the models taking into account the error of the initial data. The correction of the physicochemical model was made using results of Raman spectroscopy. The dependence of the maximum of the “borate anomaly” on the number of non-bridging oxygen atoms was shown. It was found that the most obvious changes in the dependence of properties occur in the regions of N1 and N2 compositions, which are characterized by the appearance of asymmetric triangles BØ2O− and BØO22− in glasses, correspondingly.

Far-Field Correlations Verifying Non-Hermitian Degeneracy of Optical Modes.

An experimental verification of an exceptional point (EP) in a stand-alone chaotic microcavity is a tough issue because as deformation parameters are fixed the traditional frequency analysis methods cannot be applied any more. Through numerical investigations with an asymmetric Reuleaux triangle microcavity (ARTM), we find that the eigenvalue difference of paired modes can approach near-zero regardless of nonorthogonality of the modes. In this case, for a definite verification of EPs in experiments, wave function coalescence should be confirmed. For this, we suggest the method of exploiting correlation of far-field patterns (FFPs), which is directly related to spatial mode patterns. In an ARTM, we demonstrate that the FFP correlation of paired modes can be used to confirm wave function coalescence when an eigenvalue difference approaches near zero.

Zero-order-free complex beam shaping

The unwanted zero-order diffraction is still an issue in beam shaping using pixelated spatial light modulators. In this paper, we report a new approach for zero-order free beam shaping by designing an asymmetric triangle reflector and introducing a digital blazed grating and a digital lens to the phase hologram addressed onto the spatial light modulator. By adding the digital lens phase to the previously reported complex-amplitude coding algorithms, we realized the generation of complex beams without the burden of zero-order diffraction. We comparatively investigated the produced complex light fields using a modified complex-amplitude coding algorithm to validate the proposed method.

A Compact Asymmetrical Triangular Truncated Polygon Super Wideband Microstrip Antenna for Wireless Communication Applications

The rapid growth in wireless communications of today’s era requires a new generation of antennas whose operating frequency range is greater than the FCC allocated UWB (3.1-10 GHz) frequency range and also operate simultaneously for multiple communication standards in single band of frequency. Microstrip antennas technology provides these features. A ubiquitous compact asymmetrical triangle truncated polygon structure monopole fed super wideband microstrip antenna for wireless communication is proposed in this paper. The antenna uses a compact size of 50X40 mm.2 The irregular tapered truncations on patch geometry have potential effects on enlargement of operating frequency band. The antenna is designed using modified epoxy substrate material of ε= 4.2, h=1.6 mm at 3 GHz, fabricated and measured. The measured results confirm that the antenna has operating frequency band of 1.2-20.03 GHz (177.39%) with bandwidth ratio of 16:1. The antenna has stable radiation patterns and consistent gain over operating band. The time domain group delay of antenna is within 4 ns, which indicates good linear phase response. Furthermore, this proposed antenna is able to cover the DVB-H in L-band for PMP (1.45-1.49 GHz), DCS, PCS, UMTS, Bluetooth, WiMAX2500, LTE2600 and UWB bands applications.

Graph clustering using triangle-aware measures in large networks

Graph clustering (also referred to as community detection) is an important topic in network analysis. Although a large amount of literature has been published on the problem, most of them are designed at the level of lower-order structure of networks, e.g., individual vertices and edges, and fail to capture higher-order information of networks. Recently, higher-order units (under the name of motifs) are introduced to graph clustering. These methods typically focus on constructing a motif-based hypergraph where higher-order information is preserved, and communities abstracted from the hypergraph usually achieve better accuracy. However, the hypergraph is often fragmented for a sparse network and contains a large number of isolated vertices that will be outliers of the identified community cover. To address the fragmentation problem, we propose an asymmetric triangle enhancement approach for graph clustering, in which a mixture of edges and asymmetric triangles is taken into consideration for cluster measures. We also design an approximation model to speed up the algorithm by estimating the measures. Extensive experiments on real and synthetic networks demonstrate the accuracy and efficiency of the proposed method.

Strategic Triangles and Balancing in World Politics

Trilateral diplomacy is a common format of interaction in international relations, which forms various configurations of the balance of power within the framework of triangles. The concept of a “triangle” is characterized by ambivalence, has a variety of characteristics and principles of formation.The article provides an overview of the theoretical discourse on strategic triangles, as well as of practical examples of trilateral diplomacy of the past and present day. The main characteristics of strategic triangles and the features of changes in their configuration are identified (the case of USA–PRC–USSR triangle). Classification of both symmetric and asymmetric triangles (unicenter and bicenter) are given, the concept of buffer states, as well as regional conflicts with the participation of a great power as a defender, are presented.The most influential countries at the global and regional levels, forming geopolitical triangles, are identified basing on the Composite Index of National Capability (CINC). The concept of pivot states is analyzed permitting to indicate relatively small but geopolitically important countries, forming triangles together with influential states.The main strategic triangles of the modern world order are analyzed, presenting mostly countries of Asia (China, Japan, India), Russian Federation, USA and EU. The main trends of global competition based on geopolitical triangles in the XXI-st century are identified.

Depinning behavior of the vortex domain wall at the asymmetric triangular notch in permalloy wires

The depinning field (H D) of vortex domain walls in a permalloy wire with an asymmetric triangle notch was investigated through magneto-optic Kerr effect (MOKE) microscopy and micromagnetic simulations. Wires of various widths with notches fixed on the wall’s incoming side angle were studied for various outgoing side angles (ϕ). The curves of H D of wall versus ϕ were measured by MOKE microscopy. Micromagnetic simulations were used to obtain curves of the H D of the wall versus ϕ. The maximum of such a curve of tail-to-tail -clockwise wall is known as the transition angle (ϕ T). The shape-anisotropic energy (E A) of the notch outgoing side wire and the exchange energy (E Ex) of the wall–notch interaction competed to influence the ϕ T value. Pinning potential was increased by the E Ex when ϕ was smaller than the ϕ T. Pinning potential was considerably reduced by the small E A when ϕ was larger than the ϕ T. Furthermore, the ϕ T value changed with the decrease in the depth of the notch because E A was influenced by notch depth.

Pyramidal Systems in Resistance Training

Pyramidal systems refer to a particular type of resistance training in which sets are performed with increasing (or decreasing) weight, in such a way that the number of repetitions is low when the weight is high (and vice versa). Multiple implementations exist such as the light-to-heavy, triangle or asymmetric triangle system. They are similar to traditional training, but with slightly different impact on training volume, endurance or power outcome. Therefore, pyramidal systems are ideal candidates for practitioners willing to tune their training routine.

The Mesolithic Research of a Decade: Early Holocene Settlements in Transdanubia

Despite the promising research trends of the last decades, it is striking that traces of Mesolithic settlements have only rarely come to light in the Carpathian Basin so far. The area of Transdanubia is not an exception. With the cooperation of three institutes, a research program was launched in 2003 with the aim of discovering new find places of the period, as well as re-evaluating finds that had been taken to museums earlier and classified as Mesolithic. The field surveys revealed Early Holocene sites in the South-East Transdanubian region in the valley of the Kapos and Koppány Rivers, mainly in the outskirts of Kaposhomok and Regöly. The sites mainly came to light on the island-like reliefs elevating only a few meters from the present-day floodplain. The dating of the surface finds, especially chipped stone artefacts, was primarily based on the geometric microliths, which contain asymmetric triangles, segments, and trapezes. We could even reveal Mesolithic finds within stratigraphic position at the site of Regöly 2, where the remains of a domestic structure also came to light.

Three Group Classification Problem Approach Based on Fuzzy Goal Programming

In this study, a new fuzzy logic and mathematical programming based model was proposed to solve three-group classification problem. Determination of cut-off value, which corresponds to discrimination axis in classification problems, has importance. Status of the cut-off value such as asymmetric triangle fuzzy number, trapezoid fuzzy number and gauss fuzzy number was examined. The proposed approach displayed better performance when compared to Fisher's Linear Discriminant Function and some mathematical programming-based models by using three group data sets used frequently in the literature.

Field-matter interactions of triangular apertures and lattices: symmetry breaking with frequency selection and polarization filtering

Interaction of electromagnetic (EM) waves with asymmetric triangular apertures and lattices are studied theoretically with analytical solutions and numerical simulations, where the physical symmetry and degeneracy are removed and the diffraction show distinct angular and spatial dependence on the incident EM-wave frequency. The center of the 0th-order diffraction spot for an asymmetric triangular aperture is off-axial and frequency-dependent, which is contrary to conventional symmetric apertures. For asymmetric triangular lattices, an incident wave of a given polarization state can be diffracted into several reflection and transmission modes determined by the EM frequency and lattice structures, and it is available to manipulate the number of diffraction orders as well as the EM-wave polarization and handedness. The theoretical simulations suggest that the asymmetric triangle apertures and lattices have the potential applications in angle-resolved wave scattering detectors, economic spectrum analyzers, tunable frequency filters, polarization beam splitters, and polarization controllers.

Magnetotransport in fractal network with loop sub-structures: Anisotropic effect and delocalization

We make an in-depth analysis of electronic transport and localization properties of non-interacting electrons in a Sierpinski gasket (SPG) fractal lattice in presence of magnetic field within a tight-binding framework. Unlike conventional symmetric systems, asymmetric SPG triangle leads to more conducting behavior, and thus delocalization of energy states, which we examine by calculating magnetic flux driven circular current and inverse participation ratio. The spectral peculiarity, that is the gapped nature of energy spectrum in fractal lattices, is clearly reflected from the variation of current with electron filling, yielding possibilities of getting filling dependent switching action. The effect of temperature is also discussed. Our analysis can be utilized to study magnetotransport properties in any other fractal lattices having loop sub-structures.

Directed transport of liquid droplets on vibrating substrates with asymmetric corrugations and patterned wettability: a dissipative particle dynamics study

ABSTRACTThe development of digital (droplet-based) microfluidic (DMF) devices has received significant attention due to their importance for chemical and biomedical analyses. The precise control and manipulation of liquid droplets on a solid substrate is a major requirement for DMF devices. In this study, we propose a novel strategy to generate continuous droplet motion by combining asymmetric corrugations and patterned wettability on a vibrating substrate. The time periodic oscillations of the substrate with asymmetric triangle corrugations provide the input energy to transport a droplet along patterned stripes. Using dissipative particle dynamic (DPD) simulations, we demonstrate that hydrophobic stripes on a superhydrophobic substrate create a wettability step, which effectively constrains the droplet motion along the stripe. Due to the special design of asymmetric triangle corrugations and orientation of hydrophobic stripes, the proposed strategy enables the transport of multiple droplets with different initial locations towards a single spot and coalescence into a large droplet. We further identify a power-law dependence between the droplet velocity and the period of substrate vibration and show that this function is independent of the droplet size. The proposed droplet transportation strategy can be potentially useful for the efficient manipulation of liquid droplets in DMF devices.

Optimization of Light Management Layers for Light Harvest of Perovskite Solar Cells

Recently, with rapid development of perovskite solar cells, the record efficiency has exceeded 24.2%. However, the research of efficiency improvement never stops. This work introduces an effective approach to remarkably reduce the device reflection loss by using light management (LM) cover layer. A specific model combined with ray and wave optics was built to numerically optimize the texture of the LM layers for light harvesting in photovoltaics cells and explore the optical principles in the light trapping. The LM layer texture is made of 2D periodic triangle structures. Both symmetric and asymmetric triangle structures were investigated. The results indicate that asymmetric structures possess the close performance compared with symmetric ones, and notably, on contrary to the symmetric structures, the light trapping abilities are much more insensitive to the bottom thicknesses of asymmetric structures. It will benefit the practical fabrication, since the precise bottom thickness control can be avoided. From the optimization results, 3 optimal structures are found. With the optimal LM layers, a thin active layer (165nm) device is able to produce the short circuit current intensities (Jsc) of around 21mA/cm2, which is approximately equivalent to the Jsc of a thick active layer (800nm) device without LM layers. Meanwhile, about 23% power conversion efficiency (PCE) enhancement is achieved. On the other hand, active layer thickness also makes influence on the light trapping abilities. As the active layer thickness is increased from 165nm to 800nm, the Jsc only improves by about 2.4mA/cm2, while the PCE enhancement is dropped from ~23% to ~11%. In consideration of the compromise between total device energy output and PCE enhancement, as well as material cost reduction, the active layer with around 165nm should be an optimal thickness.

Minimum foundation size and spacing for jacket supported offshore wind turbines considering dynamic design criteria

Modes of vibration play a dominant role in the design of WTG (Wind Turbine Generator) support structures. It is necessary to choose the overall system frequency such that the modes of vibration do not coincide with the rotor frequencies as well as the wave frequencies. WTG supported on multiple foundations (such as jackets or seabed frames) may exhibit rocking modes of vibration if the vertical stiffness of the foundation is not large enough which in turn may have serious implications on the fatigue performance of the overall structure. From the O&M (Operation and Maintenance) point of view, it is necessary to design the overall system to have sway-bending as the dominant mode of vibration. This paper develops a formulation for obtaining foundation (for both piles and shallow suction caissons) sizes and spacing such that rocking vibrations are prevented and sway-bending vibrations are achieved. Expressions for the minimum vertical stiffness of foundations are proposed for different configurations: square base, symmetrical (equilateral) triangle, or asymmetrical (isosceles) triangle. Verification of the method is carried out through finite element analysis and a step-by-step solved example is taken to show the application of the formulation. It is hoped that the formulation will assist designers to optimize the foundation arrangement and provide preliminary sizing for tender design.