Specific Range Research Articles

Numerical simulation of ultrasonic impact treatment (UIT) assisted laser directed energy deposition (DED) CrCoNi medium entropy alloy process

In order to enhance the microstructure and mechanical properties of additively manufactured metal parts, the application of ultrasonic impact treatment (UIT) after the additive manufacturing process is introduced as a means to modulate and optimize the material's microstructure and properties. This study systematically investigates the effect of UIT on the distribution of residual stresses in CrCoNi medium entropy alloy (CrCoNi-MEA) through numerical simulation. A suitable finite element model and boundary conditions are established to simulate the UIT assisted laser DED process. The reliability of the finite element model is verified by XRD residual test results and EBSD observation results. The numerical simulation results shows that the specimen's surface exhibited predominantly compressive stress within a specific depth range, with the maximum compressive stress in the vertical direction. Furthermore, it is observed that UIT amplitude, frequency, and impact needle diameter also significantly influenced the residual stresses. By appropriately adjusting the UIT parameters, the magnitude and distribution of residual stresses could be further controlled and regulated. In addition, it is found that multiple UITs at different surface locations exhibited no significant mutual influence between each other.

Biomass Activated Carbon: The Electrode Material to Promote the Large-Scale Production of Supercapacitors

Supercapacitors have emerged as one of the devices most likely to facilitate major breakthroughs in energy storage technology. With the advantages of wide source of raw materials, good electrical conductivity and easy preparation, biomass activated carbon has become the most promising materials to promote for application of supercapacitors. Biomass activated carbon still has problems such as low energy density and unenvironmentally preparation process. This work summarizes the relevant research about the manufacture of biomass activated carbon for supercapacitors in recent years, including the consistency between theoretical performance and experimental data, and the correlation between preparation technology and basic characteristics. Furthermore, the specific range of basic characteristics for high-performance biomass activated carbon was pointed out, which were pore size distribution, conductivity, specific surface area and surface heteroatom doping. The most suitable manufacturing process for high performance biomass activated carbon was demonstrated. This significance was important for promoting the large-scale production of biomass activated carbon for Supercapacitors.

Discharge characteristics of a low-pressure geometrically asymmetric cylindrical capacitively coupled plasma with an axisymmetric magnetic field

We investigate the discharge characteristics of a low-pressure geometrically asymmetric cylindrical capacitively coupled plasma discharge with an axisymmetric magnetic field generating an E × B drift in the azimuthal direction. Vital discharge parameters, including electron density, electron temperature, DC self-bias, and electron energy probability function (EEPF), are studied experimentally for different magnetic field strength (B) values. A transition in the plasma parameters is observed for a specific range of magnetic fields where the discharge is highly efficient with lower electron temperature. Outside this range of magnetic field, the plasma density drops, followed by an increase in the electron temperature. The observed behavior is attributed to the transition from geometrical asymmetry to magnetic field-associated symmetry due to reduced radial losses and plasma confinement in the peripheral region. The DC self-bias increases almost linearly from a large negative value to nearly zero, i.e., it turns into a symmetric discharge. The EEPF undergoes a transition from bi-Maxwellian for unmagnetized to Maxwellian at intermediate B and finally becomes a weakly bi-Maxwellian at higher values of B. The above transitions present a novel way to independently control the ion energy and ion flux in a cylindrical capacitively coupled plasma system using an axisymmetric magnetic field with an enhanced plasma density and lower electron temperature that is beneficial for plasma processing applications.

Combining laser speckle imaging and spatially modulated visible illumination to study the effect of anesthetic drugs on the optical and physiological parameters of brain

This work employs an integrated optical imaging system to evaluate the effect of anesthetic drugs on several brain parameters including absorption, scattering, oxygen saturation, and cerebral blood flow (CBF). Two anesthetic drugs, namely ketamine-xylazine (KX) and thiopental, frequently used by researchers in mouse experiments, were investigated herein. The combined system is based on spatially modulated visible light illumination and a laser speckle based-technique. With this apparatus, a series of structured light (sinusoidal patterns) with phase shifts at each of two spatial frequencies (low and high) are projected onto the surface of a mouse brain and diffusely reflected light is acquired by a camera. A six-position filter wheel, equipped with five visible bandpass filters, is placed at the output of the projector. Then, structured illumination is blocked and a laser source illuminates the tissue while the diffusely reflected light is captured by the same camera through the remaining open hole in the wheel. In this manner, visible and laser speckle images are captured and processed off-line to reconstruct the cerebral tissue features. This work's major findings are six-fold: first, over a specific range of the spectrum a difference of more than 20% was found in the absorption coefficient presumably as a sensitivity to hemoglobin. Second, a difference of more than 20% was observed between drug types in the scattering coefficient along the entire spectral range. Third, CBF varied considerably in thiopental anesthesia throughout the experiment. Fourth, oxygen saturation level remains stable in both anesthetics. Fifth, thiopental keeps blood glucose in normal range while with KX glucose level increases. Sixth, the co-registered system is capable of revealing quantitative functional contrast and may be an attractive method in a variety of biomedical applications. Overall, these findings suggest that the choice of KX or thiopental should be carefully considered as a component of study design in research utilizing animal models.

Critical Decay Time Model for Direct Detonation Initiation Energy in Gaseous Mixtures

A critical decay time (CDT) model is developed to predict the critical energy of direct detonation initiation in gaseous mixtures. It is based on the global initiation criterion that the energy deposit should allow the decaying shock speed to stay in a specific range below the Chapman–Jouguet (CJ) speed at least for a critical decay time. The speed range is estimated with the sub-CJ Zel’dovich–von Neumann–Döring (ZND) simulations. The critical decay time is calculated as the minimum time to reach unity Mach number in the sub-CJ ZND simulations. The lower-speed bound is taken as a characteristic extinction speed below (which means the lower-speed bound) which the direct initiation should fail. This speed is calibrated using one-dimensional simulations for hydrogen (H2)–oxygen (O2)–argon (Ar) mixtures. The calibrated CDT model is then applied to estimate the critical initiation energy with the point-blast theory. The model yields better agreement with experimental data for hydrogen-fueled mixtures such as H2─O2─Ar and H2─air mixtures than the well-known critical decay rate model. For small hydrocarbon-fueled mixtures such as acetylene (C2H2)─O2─Ar, methane (CH4)–air, ethylene (C2H4)–air, and ethane (C2H6)─air mixtures, the predicted critical energies also agree well with experimental results. The CDT model provides an efficient tool to evaluate the detonability of fuel–oxidizer mixtures, which could be beneficial for ignition initiation in propulsion and power devices such as rotating detonation engines.

Numerical study on dissolution characteristics of solid-phase oxygen control in liquid LBE systems based on the porous media model

For the proper design and operation of lead oxide mass exchanger (PbO MX), the dissolution kinetics of PbO in flowing liquid Lead-bismuth eutectic (LBE) needs to be determined. A computational fluid dynamics (CFD) method of the PbO MX was established. The solid-phase oxygen control part of the MX is PbO spheres packed bed, which is regarded as a porous media in the simulation calculation. The oxygen mass transfer process between PbO spheres packed bed and liquid LBE was simulated by a porous media model with the species transport model. The relationship between the dissolution rate of MX and the flow rate, temperature and initial oxygen concentration is predicted. The dissolution rate of PbO increases exponentially with increasing temperature of LBE. Besides, the dissolution rate of oxygen is positively correlated with the LBE flow velocity. In the specific oxygen concentration range, the MX inlet oxygen concentration has little effect on the dissolution rate. The smaller the porosity of PbO spheres packed bed has, the smaller the dissolution rate of oxygen is. Furthermore, when the porosity is constant, the dissolution rate of oxygen increases with the increase of the height of the packed bed of PbO spheres.

A comprehensive discussion for the identification of cracking points in f(R) theories of gravity

This paper investigates the concept of cracking and overturning to analyze the impact of local density perturbations on the stability of self-gravitating compact objects in the framework of f(R,phi , X) theory of gravity, where R, phi , and X denote the Ricci scalar, scalar potential, and kinetic term, respectively. In this context, we developed the hydrostatic equilibrium equation for spherically symmetric spacetime with anisotropic matter configuration and subsequently employed the Krori Barua technique. We then perturb the hydrostatic equilibrium state of the configuration by employing the local density perturbation technique, while taking into account the barotropic equation of state. To validate this technique, we employed it on different compact stars namely, Her X-1, SAX J1808.4-3658, 4U 1820-30, PSR J1614-2230, Vela X-1, and Cen X-3, and found that all stars exhibit cracking or overturning for a specific range of model parameters. Conclusively, this study emphasizes that the proposed cracking technique provides significant insights into the stability analysis of self-gravitating compact objects.

Insights into acoustic properties of seven selected triply periodic minimal surfaces-based structures: A numerical study

Poly(methyl methacrylate)-based triply periodic minimal surfaces (TPMS) structures promise great potential in phononic applications, but the complicated TPMS structure induces a design challenge for controlling their properties. Numerical acoustic simulations of seven major PMMA-based TPMS lattice structures are presented for low-frequency sound attenuation applications while varying their relative density. Except for the local resonances in primitive and Neovius-based lattice structures, the acoustic properties of other TPMS structures show a common Bragg bandgap with a central frequency of around 435 Hz and a bandwidth of around 286 Hz, which results from multiple scattering of periodic unit cells. In contrast, the acoustic bandgaps of primitive and Neovius-based lattices have much smaller and larger complete bandgaps, respectively, which are mainly attributed to the local resonances in their geometric cavities with different sizes. Thus, by taking the mechanism of generated bandgaps in the TPMS-based lattice structures into consideration, we can design suitable bandgaps for acoustic applications in the specific frequency range.

Proposing a Hybrid BTMS Using a Novel Structure of a Microchannel Cold Plate and PCM

The battery thermal management system (BTMS) for lithium-ion batteries can provide proper operation conditions by implementing metal cold plates containing channels on both sides of the battery cell, making it a more effective cooling system. The efficient design of channels can improve thermal performance without any excessive energy consumption. In addition, utilizing phase change material (PCM) as a passive cooling system enhances BTMS performance, which led to a hybrid cooling system. In this study, a novel design of a microchannel distribution path where each microchannel branched into two channels 40 mm before the outlet port to increase thermal contact between the battery cell and microchannels is proposed. In addition, a hybrid cooling system integrated with PCM in the critical zone of the battery cell is designed. Numerical investigation was performed under a 5C discharge rate, three environmental conditions, and a specific range of inlet velocity (0.1 m/s to 1 m/s). Results revealed that a branched microchannel can effectively improve thermal contact between the battery cell and microchannel in a hot area of the battery cell around the outlet port of channels. The designed cooling system reduces the maximum temperature of the battery cell by 2.43 °C, while temperature difference reduces by 5.22 °C compared to the straight microchannel. Furthermore, adding PCM led to more uniform temperature distribution inside battery cell without extra energy consumption.

Adjustable Elasticity of Anatomically Shaped Lattice Bone Scaffold Built by Electron Beam Melting Ti6Al4V Powder

This study investigates the elasticity of specific lattice structures made from titanium alloy (Ti6Al4V), namely, anatomically shaped lattice scaffolds (ASLS) aimed for reinforcement of the bone tissue graft that substitute a missing piece of the previously injured bone during its recovery. ASLSs that were used for testing were fabricated using the Electron Beam Melting (EBM) method. The mechanical properties of the ASLS were examined through uniaxial compression tests. Compression testing revealed the complex non-linear behavior of the scaffold structure’s elasticity, with distinct compression stages and deformation dependencies. The ASLS structures exhibited quasi-elastic deformation followed by the rupture of individual struts. Results demonstrate that the ASLSs can be stiffened by applying appropriate compression load and accordingly achieve the target elasticity of the structure for the specific load range. The modulus of elasticity was determined for different compression stages of ASLS, allowing interpolation of the functional relation between the modulus of elasticity and compressive force that is used for stiffening the ASLS. This study enhances the understanding of the mechanical behavior of the specific lattice structures made of Ti6Al4V and provides insights for the development of mechanically optimized anatomically shaped lattice scaffolds.

Experimental study of the strengthening effect: A novel fatigue life prediction method for variable amplitude loads

AbstractThe strengthening effect of low‐amplitude loading at elevated temperatures was investigated experimentally. A powder metallurgy nickel‐based superalloy FGH96 was preloaded with different cycle numbers and stress levels, and the residual fatigue life was tested under subsequent high‐amplitude loads. The results show that when the number of preloading cycles is in a specific range, the residual fatigue life is higher than that of the virgin specimen under the same load. A novel damage accumulation model was proposed to incorporate the strengthening effect into the life prediction framework. The proposed model was validated using experimental results for various materials in the literature. The mechanism of the strengthening effect of FGH96 was discussed based on electron backscatter diffraction (EBSD) analysis.

Functional non-uniformity of periodontal ligaments tunes mechanobiological stimuli across soft- and hard-tissue interfaces

The bone-periodontal ligament-tooth (BPT) complex is a unique mechanosensing soft-/hard-tissue interface, which governs the most rapid bony homeostasis in the body responding to external loadings. While the correlation between such loading and alveolar bone remodelling has been widely recognised, it has remained challenging to investigate the transmitted mechanobiological stimuli across such embedded soft-/hard-tissue interfaces of the BPT complex. Here, we propose a framework combining three distinct bioengineering techniques (i, ii, and iii below) to elucidate the innate functional non-uniformity of the PDL in tuning mechanical stimuli to the surrounding alveolar bone. The biphasic PDL mechanical properties measured via nanoindentation, namely the elastic moduli of fibres and ground substance at the sub-tissue level (i), were used as the input parameters in an image-based constitutive modelling framework for finite element simulation (ii). In tandem with U-net deep learning, the Gaussian mixture method enabled the comparison of 5195 possible pseudo-microstructures versus the innate non-uniformity of the PDL (iii). We found that the balance between hydrostatic pressure in PDL and the strain energy in the alveolar bone was maintained within a specific physiological range. The innate PDL microstructure ensures the transduction of favourable mechanobiological stimuli, thereby governing alveolar bone homeostasis. Our outcomes expand current knowledge of the PDL's mechanobiological roles and the proposed framework can be adopted to a broad range of similar soft-/hard- tissue interfaces, which may impact future tissue engineering, regenerative medicine, and evaluating therapeutic strategies. Statement of significanceA combination of cutting-edge technologies, including dynamic nanomechanical testing, high-resolution image-based modelling and machine learning facilitated computing, was used to elucidate the association between the microstructural non-uniformity and biomechanical competence of periodontal ligaments (PDLs). The innate PDL fibre network regulates mechanobiological stimuli, which govern alveolar bone remodelling, in different tissues across the bone-PDL-tooth (BPT) interfaces. These mechanobiological stimuli within the BPT are tuned within a physiological range by the non-uniform microstructure of PDLs, ensuring functional tissue homeostasis. The proposed framework in this study is also applicable for investigating the structure-function relationship in broader types of fibrous soft-/hard- tissue interfaces.

Flexible Capacitive Sensors Based on Liquid Crystal Elastomer.

The disordered transformation of the ordered aligned polar liquid crystal molecules in liquid crystal elastomers (LCEs) under the influence of an external field imbues them with the unique property of thermally reversible shape memory, making them highly valuable for various applications, particularly in actuators. In this study, we examined the high dielectric constant exhibited by the orientation polarization of polar liquid crystal molecules in RM257-LCE films, which holds significant potential for developing flexible capacitive sensors. By manipulating the flexibility of the molecular chain network and introducing hydrogen bonds and metal ions into the main chain, we were able to enhance the relative dielectric constant of LCEs to an impressive value of 62 (at 100 Hz), which is approximately 23 times higher than for polydimethylsiloxane (PDMS). This elevated dielectric constant displays a noteworthy positive temperature coefficient within a specific temperature range, starting from room temperature and extending to the clearing point. Using this property, we fabricated highly sensitive capacitive, flexible temperature sensors. Moreover, we successfully engineered a flexible pressure sensor with an excellent pressure-sensing range of 0-2 MPa by combining the porous structure of the prepared LCEs with mushroom electrodes. Additionally, the sensor showcases a remarkable capacitance recovery time of 0.8 s at 90 °C. These outstanding features collectively contribute to the excellent pressure-sensing characteristics of our sensor. The findings of this study offer valuable insights and serve as a reference for the design of innovative flexible sensors, enabling advancements in sensor technology.

Adaptive predictive control of a fan-ventilated tunnel greenhouse with evaporative cooling

In the present work, micro-climate control of a fan-ventilated tunnel greenhouse with evaporative cooling is investigated via simulation study. For this purpose, the adaptive generalized predictive control (AGPC) strategy is adopted to control temperature, relative humidity, and CO2 concentration in the greenhouse on extremely hot summer days. A dynamic model which integrates a distributed model of greenhouse micro-climate with a crop growth model is used for numerical simulation of the tunnel greenhouse. The controller performance is analyzed via numerical simulation. The relative gain array analysis confirms that greenhouse micro-climatic parameters are highly interactive. However, simulation results showed that AGPC can efficiently handle variables interaction and follow set-points despite actuator limitations and high outside temperature. Besides, by considering output constraints in applying AGPC, the control system can keep the humidity of the greenhouse in a specific range instead of in a particular set point. The calculation burden for the AGPC strategy is kept low without increasing prediction error by employing a linear model and on-line adaptive identification. The applied strategy can handle the uncertainty of the design model due to the model mismatch by on-line identification of model parameters using the recursive least square method.

Determination of Oil Quality and Antifungal Effect of Selected Citronella Accessions (Cymbopogon nardus, Cymbopogon winterianus) to Formulate an Anti-Dandruff Shampoo

Citronella is an aromatic grass of the family Poaceae which can be classified into two categories Ceylon Citronella (Cymbopogon nardus) and Java Citronella (Cymbopogon winterianus). The Citronella oil was extracted from five selected Ceylon Citronella (HP T1, HP T2 and HP T3) and Java Citronella (MP T1 and MP T2) accessions using steam distillation and hydrodistillation methods. Citronella oil quantity extracted by hydrodistillation with Xylene from Ceylon Citronella was higher (2.45-2.67 mL/100 g) than the Java Citronella (1.57-1.64 mL/100 g). The oil quantity of Ceylon Citronella (HP T1-5.52 %, HP T2- 1.40 %, HP T3- 1.05 %) and the quantity of Java Citronella (MP T1- 1.25%, MP T2- 1.79%) extracted by hydrodistillation showed a significant difference (P<0.0001) and there was no significant difference (P=0.7055) between the oil quantity of Ceylon (HP T1- 1.07%, HP T2- 1.18 %, HP T3- 1.19%) and Java (MP T1- 1.16%, MP T2- 1.23%) oils extracted by the steam distillation. Both Java and Ceylon Citronella oils showed organoleptic properties with pale yellow to pale brownish yellow colour and a strong citrusy aroma which meets the ISO 3848 and ISO 3849 standards. The oil of Ceylon Citronella accessions showed refractive index (1.465-1.487), relative density (0.893-0.910), and ethanol solubility (1:2 mL) within the ranges specified in SLS 170 standards. Java Citronella oil exhibited the refractive index (1.4660-1.4730), relative density (0.880-0.892), ethanol solubility (1:2 mL), and optical rotation (-5? to 0?) which meets the specifications of ISO 3848 standards. Geraniol, Citronellol, and Citronellal were identified as the major constituents using the gas chromatography-mass spectrometry (GC-MS) where Java Citronella oil showed high Geraniol content (48.60-49.17%) than Ceylon Citronella oil (16.93-26.49%). All types of tested Citronella oil showed inhibition against Candida albicans where HP T3 (1.9 cm) and MP T1(2.0 cm) oils showed the highest promising antifungal activity among Ceylon oils and Java oils respectively. Therefore, these two oils were selected for the antidandruff shampoo formulation. The two antidandruff shampoo samples were formulated with 2% v/v concentrations of HP T3 and MP T1 Citronella oil which were determined as MIC for the inhibition of C. albicans. Antidandruff shampoo tested against C. albicans showed greater antifungal activity (HP T3 - 2.50.05 cm; MP T1 - 2.50.05 cm) than the crude Citronella oil (HP T3- 1.90.11 cm; MP T1-2.00.1 cm), also attained the organoleptic and physical properties such as pH (4.0-8.0), foam height (>100 mL), dirt dispersion (no ink in foam), viscosity, low wetting time and solid content (HP T3-14.750.12%; MP T2-12.330.19%) in acceptable specification range. This study exhibits that Ceylon Citronella oil HP T1 has the highest oil quantity from all selected accessions. Hydrodistillation can be used to extract high oil quantity than the steam distillation method from both Java and Ceylon Citronella types. Compared to Ceylon Citronella oil, Java oil has significant potential industrial applications with high Geraniol content and with the highest antifungal activity against C. albicans. Also, the tested Citronella oil of all selected accessions of both Java and Ceylon types meet the organoleptic and physiochemical requirements specified by the ISO and SLS quality standards with excellent antifungal activity against C. albicans, which provides prospective to use Citronella oil as a natural, safe, and eco-friendly fungicide in future product formulations.

Changes in pH and Nitrite Nitrogen Induces an Imbalance in the Oxidative Defenses of the Spotted Babylon (Babylonia areolata).

In order to reveal the acute toxicity and physiological changes of the spotted babylon (Babylonia areolata) in response to environmental manipulation, the spotted babylon was exposed to three pH levels (7.0, 8.0 and 9.0) of seawater and four concentrations of nitrite nitrogen (0.02, 2.7, 13.5 and 27 mg/L). The activities of six immunoenzymes, superoxide dismutase (SOD), glutathione peroxidase (GSH-PX), catalase (CAT), acid phosphatase (ACP), alkaline phosphatase (AKP) and peroxidase (POD), were measured. The levels of pH and nitrite nitrogen concentrations significantly impacted immunoenzyme activity over time. After the acute stress of pH and nitrite nitrogen, the spotted babylon appeared to be unresponsive to external stimuli, exhibited decreased vigor, slowly climbed the wall, sank to the tank and could not stand upright. As time elapsed, with the extension of time, the spotted babylon showed a trend of increasing and then decreasing ACP, AKP, CAT and SOD activities in order to adapt to the mutated environment and improve its immunity. In contrast, POD and GSH-PX activities showed a decrease followed by an increase with time. This study explored the tolerance range of the spotted babylon to pH, nitrite nitrogen, and time, proving that external stimuli activate the body's immune response. The body's immune function has a specific range of adaptation to the environment over time. Once the body's immune system was insufficient to adapt to this range, the immune system collapsed and the snail gradually died off. This study has discovered the suitable pH and nitrite nitrogen ranges for the culture of the spotted babylon, and provides useful information on the response of the snail's immune system.

Thermocapillary thin film flows on a slippery substrate with odd viscosity effects

This study investigates the behavior of a thin liquid with odd viscosity effects as it flows down a uniformly heated, slippery inclined plane, where the liquid’s time-reversal symmetry is broken. The breaking of symmetry results in interesting effects, as the antisymmetric part of the fluid stress tensor does not vanish. Two models, the Benney-type equation model (BEM) and the weighted residual model (WRM), are constructed to account for the combined effects of slip length, thermocapillarity, and odd viscosity. A detailed stability analysis determines both models’ critical Reynolds numbers Rec. For small slip lengths, the first-order WRM is better at capturing the instability threshold than the first-order BEM. While both models account for the effects of odd viscosity and thermocapillarity, only the Rec of WRM incorporates the wall slip effects. Another significant finding is that the BEM effectively avoids the issue of finite-time blow-up by incorporating odd viscosity. Additionally, employing a weakly nonlinear stability analysis with multiple scales uncovers four flow regions in BEM: supercritical stable, subcritical unstable, unconditional stable, and explosive zones. Two separate bifurcation scenarios emerge for various wave numbers: supercritical within a specific range and subcritical for larger wave numbers. The presence of odd viscosity alleviates the reduction of the unconditional stable zone and the increase in the explosive zone, which are caused by the combined influence of slip and thermal effects. Numerical investigation of traveling wave solutions of WRM shows that wave height is promoted by slip and thermal effects but reduced with increasing odd viscosity coefficient. Further numerical simulations of WRM on a larger domain demonstrate the stabilizing effects of odd viscosity and its interaction with destabilizing slip and thermocapillary effects.

Vibration wave propagation differences in straight assembled shield tunnels under different deformation conditions

During the implementation of shield tunnel construction, deformation and joint opening may arise as a result of load-induced influences. Recent research has highlighted the crucial role of segment joints in the dynamic analysis of shield tunnels, yet a comprehensive understanding of the influence of joint opening on vibration wave transmission is still lacking. To address this gap, this study established a finite element model of a shield tunnel and investigated the effects of joint opening on the transmission of vibration waves. The findings of this study indicate several important results: (a) The weakening ability of joints to vibration waves within a specific frequency range is closely related to the degree of joint opening. With increasing joint opening, the weakening ability of certain joints towards specific frequency vibration waves can increase by more than 40%; (b) The weakening effect of joints on vibration waves exhibits a significant correlation with the orientation of joint openings. Inward-opening longitudinal joints exhibit a high rate of weakening for vibration waves, while outward-opening longitudinal joints demonstrate limited weakening ability towards the vibration wave; (c) The weakening ability of segment concrete towards vibration waves is significantly weaker compared to that of joints. Hence, the inclusion of segment joints is crucial in the investigation of dynamics of shield tunnels, as they cannot be disregarded.

Floquet engineering-based frequency demodulation method for wireless THz short-range communications

This study introduces a novel theoretical framework for detecting and decoding wireless communication signals in the nanoscale range operating at terahertz (THz) frequencies. Initially, we investigate the Floquet states in a dressed 2D semiconductor quantum well and derive an analytical expression to determine its longitudinal conductivity. The results indicate that the longitudinal conductivity of a dressed 2D semiconductor can be tailored to specific requirements by manipulating the frequency of the external dressing field. Furthermore, carefully selecting the intensity and polarization type of the external dressing field enables fine-tuning and optimization of the conductivity. To evaluate the effectiveness of each dressing field configuration, we present a figure of Merit (FoM) assessment that determines the maximum possible change in conductivity within the considered frequency range. The proposed theory introduces a mechanism capable of identifying frequency-modulated communication signals in the THz range and performing frequency demodulation. We comprehensively analyze of the demodulator’s transfer function in the receiver. Consequently, we establish that the transfer function exhibits linear behavior over a specific frequency range, rendering it suitable for frequency demodulation. Finally, we provide a numerical illustration of a frequency demodulation scenario. The breakthrough uncovered in this study opens up possibilities for the development of high-efficiency, lightweight, and cutting-edge chip-scale wireless communication devices, circuits, and components.

Macrofungal Diversity in Selected Coastal Mangrove Ecosystems in Guyana, South America

Macrofungi in mangrove ecosystems remain understudied, especially in Guyana. An investigation of the macrofungal diversity in selected coastal mangrove ecosystems in Guyana was carried out, which yielded 19 species belonging to 18 genera, 14 families, nine (9) orders, five (5) classes and two (2) phyla. Majority of the species identified (89%) belong to the phylum Basidiomycota. Consequently, 78% of the species identified were found thriving on the stems, barks and wood above the high tide line, which accounts for the high diversity for the class Agaricomycetes (80%) and orders Polyporales (40%) and Agaricales (25%) since the majority of species are wood-based fungi.
 Sampling was done during the dry season from the overwash ecosystem of old-growth mangrove ecosystems and rehabilitated mangrove ecosystems, revealing that most of the species identified (17) belong to the old-growth mangrove ecosystems. Four (4) species (Fomes fomentarius, Gloeophyllum sepiarium, Phaeolus schweinitzii, and Schizophyllum commune) were found in the old and rehabilitated mangrove ecosystems. 
 Additionally, it was noted that environmental parameters positively and negatively affect macrofungal growth. That is, there is a specific range for each parameter in which macrofungi thrive, and if an increase or decrease beyond those ranges occurs, species diversity decreases.