Small Attenuation Research Articles

Running economy with shoes that elicit an involuntary forefoot strike in the habitual rear and non-rear foot strike runners

The metabolic benefits of non-rearfoot strike (non-RFS) running remain unknown because no interventions can alter the runner’s foot strike patterns involuntarily. This study investigated whether wearing running shoes that elicit involuntary non-RFS running alters the oxygen consumption (VO2) of habitual RFS and non-RFS runners. Twenty-three male runners (10 RFS and 13 non-RFS) performed six bouts of 5-min treadmill runs at slow or fast speeds below lactate thresholds. The first three bouts were performed using either the control shoes (traditional racing shoes), the shoes that elicit involuntary non-RFS (Wave Duel Pro [WDP]), or the additional shoe used for a different purpose. Subsequently, participants ran another three bouts wearing each shoe in mirror order. Only the control and WDP shoes were analysed in this study. All participants were non-RFS runners when wearing WDP. The VO2 did not differ between WDP and control in habitual non-RFS runners (43.7 ± 5.6 and 43.5 ± 5.6 mL kg−1 min−1, respectively, P = 0.306 for the main effect of shoes). A small attenuation of VO2 by approximately 0.9% was observed with WDP compared with control in habitual RFS runners (43.9 ± 5.4 and 44.3 ± 5.6 mL kg−1 min−1, respectively, P = 0.025 for the main effect of shoes). The blood lactate concentration did not differ between WDP and control in both groups (P ≥ 0.603). Similarly, the heart rate did not differ between the shoes in both groups (P ≥ 0.166). The involuntary induction of non-RFS running by changing shoes has a negligible effect on reducing the running economy of habitual RFS runners.

Internal radiation effect on semiconductor β-Ga2O3 crystals grown by the VB Method and anisotropic thermal stress

Gallium oxide crystals are semitransparent semiconductors with good optical and electrical properties, which allow their use for several technological applications. During the growth process of β-Ga2O3 crystals, internal radiation plays a crucial role that affects the growth process and then the crystal quality. In this work, the effect of the melt and the crystal transparency on the vertical Bridgman growth of β-Ga2O3 oxide is thoroughly studied. Using a global 2D/3D finite element model, temperature, melt flow, melt-crystal interface, and three-dimensional anisotropic thermal stress are computed at different growth stages. At each stage, four cases are considered, namely, opaque melt and crystal, semi-transparent melt and opaque crystal, semitransparent crystal and opaque melt, and finally semitransparent melt and crystal. The role of internal radiation in each case at different growth stages is then highlighted separately and then coupled together. It was found that the melt-crystal interface is shifted from a convex shape at the early stage to a nearly plane and then to a concave shape at the last stage. The melt flow is then changed from two rolls pattern at the beginning to a single-roll structure at the last stage. Thermal stress of the as-grown ingot is decreased during the growth due to the decrease of temperature non-linearities. Internal radiation inside the crystal acts to increase the melt-crystal interface convexity at the early and middle stages of the growth process and leads to a decrease in its concavity at the final stage. However, the melt transparency leads to the opposite effects, i.e., it decreases the interface convexity at the early stage and increases the interface concavity at the final stage. As a result, for semitransparent crystal and melt, the interface is between the two previous cases. The calculated thermal stresses are found to be more affected by the transparency of the crystal than the melt as the absorption coefficient of β-Ga2O3 crystal is smaller than that of the melt. At all stages, the thermal stresses are found to be larger for the opaque case due to the increase of temperature non-linearities in the crystal. Large values are found at the bottom and the lower part of the periphery. Furthermore, internal radiation inside the melt plays a major role during the early growth stage due to the large liquid volume. It reduces the melt flow intensity close to the free surface where the shear stress is combined with the buoyant force and leads to the flattening of the interface decreasing then the radial temperature gradients, which leads to small attenuation of the thermal stress. At the final stage, the transparency of the melt plays the opposite role due to the increase of the interface concavity which leads to an increase in both of the temperature gradients and the thermal stress inside the crystal. Due to the crystal anisotropy, and especially to the large thermal expansion coefficient in the [010] direction, the 3D thermal stress values are found to be larger in this direction, especially in the bottom part of the ingot. Comparisons with available experimental and numerical works are provided in this paper.

Design of Ultra-Narrow Bandgap Polymer Acceptors for High-Sensitivity Flexible All-Polymer Short-Wavelength Infrared Photodetectors.

All-polymer photodetectors possess unique mechanical flexibility and are ideally suitable for the application in next-generation flexible, wearable short-wavelength infrared (SWIR, 1000-2700 nm) photodetectors. However, all-polymer photodetectors commonly suffer from low sensitivity, high noise, and low photoresponse speed in the SWIR region, which significantly diminish their application potential in wearable electronics. Herein, two polymer acceptors with absorption beyond 1000 nm, namely P4TOC-DCBT and P4TOC-DCBSe, were designed and synthesized. The two polymers possess rigid structure and good conformational stability, which is beneficial for reducing energetic disorder and suppressing dark current. Owing to the efficient charge generation and ultralow noise current, the P4TOC-DCBT-based all-polymer photodetector achieved a specific detectivity () of over 1012 Jones from 650 (visible) to 1070 nm (SWIR) under zero bias, with a response time of 1.36 μs. These are the best results for reported all-polymer SWIR photodetectors in photovoltaic mode. More significantly, the all-polymer blend films exhibit good mechanical durability, and hence the P4TOC-DCBT-based flexible all-polymer photodetectors show a small performance attenuation (<4%) after 2000 cycles of bending to a 3 mm radius. The all-polymer flexible SWIR organic photodetectors are successfully applied in pulse signal detection, optical communication and image capture.

Design of Ultra‐Narrow Bandgap Polymer Acceptors for High‐Sensitivity Flexible All‐Polymer Short‐Wavelength Infrared Photodetectors

All‐polymer photodetectors possess unique mechanical flexibility and are ideally suitable for the application in next‐generation flexible, wearable short‐wavelength infrared (SWIR, 1000–2700 nm) photodetectors. However, all‐polymer photodetectors commonly suffer from low sensitivity, high noise, and low photoresponse speed in the SWIR region, which significantly diminish their application potential in wearable electronics. Herein, two polymer acceptors with absorption beyond 1000 nm, namely P4TOC‐DCBT and P4TOC‐DCBSe, were designed and synthesized. The two polymers possess rigid structure and good conformational stability, which is beneficial for reducing energetic disorder and suppressing dark current. Owing to the efficient charge generation and ultralow noise current, the P4TOC‐DCBT‐based all‐polymer photodetector achieved a specific detectivity () of over 1012 Jones from 650 (visible) to 1070 nm (SWIR) under zero bias, with a response time of 1.36 μs. These are the best results for reported all‐polymer SWIR photodetectors in photovoltaic mode. More significantly, the all‐polymer blend films exhibit good mechanical durability, and hence the P4TOC‐DCBT‐based flexible all‐polymer photodetectors show a small performance attenuation (&lt;4%) after 2000 cycles of bending to a 3 mm radius. The all‐polymer flexible SWIR organic photodetectors are successfully applied in pulse signal detection, optical communication and image capture.

Sound attenuation at low to mid frequencies in low velocity seabottoms.

Attenuation is the most difficult seafloor acoustic property to get, particularly at low to mid frequencies. For low velocity bottoms (LVB), it becomes even more challenging, due to its small attenuation and lower velocity (relative to the velocity of the adjacent water). The latter one causes a fatal "seafloor velocity-attenuation couplings" in geo-acoustic inversions. Thus, attenuation inversions for the LVB require an accurate seafloor velocity profile, especially the velocity in the LVB layer. The propagation of explosive sound in the Yellow Sea with a strong thermocline and a top LVB layer exhibits many prominent characteristics: modal dispersion (the ground wave, water wave, Airy phase), two groups of water waves at high frequencies, and the siphon effect which causes abnormally large sound transmission loss at selected frequencies, etc. These observations are used to precisely measure the critical frequency, the Airy frequency, Airy wave velocity, 1st mode group velocity, and to derive the velocities in the LVB layer and in the basement. Using inverted seafloor parameters, the source level-normalized transmission loss and the first mode decay rate in ranges up to 27.66 km, the sound attenuations in the LVB are derived for a frequency range of 13-5000 Hz.

108 m Underwater Wireless Optical Communication Using a 490 nm Blue VECSEL and an AOM.

Advanced light sources in the blue-green band are crucial for underwater wireless optical communication (UWOC) systems. Vertical-external-cavity surface-emitting lasers (VECSELs) can produce high output power and good beam quality, making them suitable for UWOC. This paper presents a 108 m distance UWOC based on a 100 mW 490 nm blue VECSEL and an acousto-optic modulator (AOM). The high-quality beam, which is near diffraction-limited, undergoes relatively small optical attenuation when using a conventional avalanche photodiode (APD) as the detector and employing 64-pulse position modulation (PPM). At the time-slot frequency of 50 MHz, the bit error rate (BER) of the UWOC was 2.7 × 10-5. This is the first reported AOM-based UWOC system with a transmission distance over 100 m. The estimated maximum transmission distance may be improved to about 180 m by fully utilizing the detection accuracy of the APD according to the measured attenuation coefficient of the blue VECSEL used. This type of UWOC system, composed of a high-beam-quality light source and a conventional detector, make it more closely suited to practical applications.

ANALISIS GANGGUAN DAN IDENTIFIKASI KABEL FIBER OPTIC MENGGUNAKAN OTDR DI OTB CIREBON-BREBES R4

Fiber optic cables that experience interference and breaks are a common problem in modern communications infrastructure. Interference and breaks in optical cables can disrupt data transmission between locations and cause a decrease in signal quality. The use of an Optical Time Domain Reflectometer (OTDR) has become a common method for detecting faults in optical cables by displaying the attenuation of the cable under test. Although optical fiber has a large capacity and high speed for transmitting information, relatively small attenuation still has a significant impact on transmission quality. The importance of maintaining and handling this interference is because attenuation can cause power loss in fiber optic transmission, hamper data transmission, and affect the quality of internet services

Matched control analysis suggests that R-CHOP followed by (R)-ICE may improve outcome in non-GCB DLBCL compared with R-CHOP

AbstractRituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) is considered the standard-of-care for patients with advanced-stage diffuse large B-cell lymphoma (DLBCL), despite findings that patients with nongerminal center B-cell like (non-GCB) have significantly worse outcome with this regimen. We evaluated the prognostic significance of baseline risk factors, including cell of origin (COO) classified by the Hans algorithm, within an alternative chemoimmunotherapy program. At Memorial Sloan Kettering Cancer Center (MSK), 151 patients with DLBCL received sequential R-CHOP induction and (R)-ICE (rituximab, ifosfamide, carboplatin, and etoposide) consolidation. Outcome analysis based on COO was validated with a propensity score–matched cohort treated with R-CHOP from the Mayo Clinic component of the Molecular Epidemiology Resource (MER). Among the patients with GCB (n = 69) and non-GCB (n = 69) at MSK, event-free survival (EFS) of non-GCB was superior to that of GCB (hazard ratio [HR], 0.53; 95% confidence interval [CI], 0.29-0.98). Overall survival (OS) demonstrated an association in the same direction but was not statistically significant (HR, 0.68; 95% CI, 0.33-1.42). Propensity score–matched patients from MSK (n = 108) demonstrated a small attenuation in the HRs for EFS (HR, 0.57; 95% CI, 0.27-1.18) and OS (HR, 0.76; 95% CI, 0.33-1.79) and were no longer statistically significant. In contrast, the matched MER cohort (n = 108) demonstrated an EFS association (HR, 1.17; 95% CI, 0.70-1.95) and OS association (HR, 1.13; 95% CI, 0.64-2.00) in the opposite direction, but were also not statistically significant. R-CHOP induction and (R)-ICE consolidation may overcome the negative prognostic impact of the non-GCB phenotype, per the Hans algorithm, and can be preferentially selected for this population. This trial was registered at www.ClinicalTrials.gov as #NCT00039195 and #NCT00712582.

Single Ru atoms dispersed on MoSe2/MXene nanosheets with multiple interfaces for enhanced acidic hydrogen evolution

Exposing more catalytic active sites is an effective strategy to enhance the catalyst activity for hydrogen evolution reaction (HER). Herein, Ti3C2Tx MXene served as a substrate to load thin and curved 2H–MoSe2 nanosheets by a typical hydrothermal method, forming MoSe2/MXene heterointerface with the fully exposed Mo edge sites. And then, atomically dispersed Ru single atoms (RuSAs) were successfully anchored on the MoSe2/MXene (RuSAs@MoSe2-MXene). The X-ray absorption near edge structure (XANES) demonstrates that Ru is loaded as single atoms on MoSe2 and MXene. The prepared sample exhibits improved catalytic activity with a small overpotential of 49 mV at 10 mA cm−2 and a low Tafel slope of 52 mV dec−1 for HER in 0.5 M H2SO4. It also exhibits excellent stability with a small attenuation voltage of 10 mV for 120 h at 10 mA cm−2 in 0.5 M H2SO4. When assembled into a two-electrode system of RuSAs@MoSe2-MXene||RuO2, it only requires a relatively low potential of 1.626 V at 10 mA cm−2 to drive overall water splitting (OWS). Control experiments disclose the highly improved performance can be primarily attributed to the introduced RuSAs and MoSe2/MXene heterointerfaces exposing more active sites of Ru and Mo. Moreover, the high conductivity of MXene can increase charge transfer in HER process. The interface engineering with multiple interfaces can provide fresh impetus for the development of efficient HER catalysts.

High-throughput screening and in vitro evaluation of CSB-0914; a novel small molecule NF-κB inhibitor attenuating inflammatory responses through NF-κB, Nrf2 and HO-1 cross-talk

Unpleasant side effects of standard inflammatory drugs urges search for novel therapeutic candidates. This study aims in identifying novel anti-inflammatory NF-κB inhibitor by high-throughput computational and in-vitro pre-clinical approaches. Lead candidate selection was conducted by the use of computational docking molecular-dynamic simulations. The RBL-2H3 cell line, derived from rat basophils, was used to evaluate the release of cytokines and degranulation. The study focused on the study of neutrophil elastase and its role in cellular motility. Flow cytometry was utilized to evaluate the activation of basophils and the expression of critical signaling proteins. High throughput screening identified CSB-0914 to stably bind NF-κB-p50 subunit. Dose based loss in T NF-α and IL-2 release were observed in RBL-2H3 cells in addition to degranulation inhibition by CSB-0914. The compound demonstrated significant efficacy in reducing basophil activation assay induced by FcεRI receptors, with an IC50 value of 98.41 nM.. A dose dependent decrease in neutrophil migration and elastase were observed when treated with CSB- 0914. The compound was effective in decreasing. Upon stimulation, RBL-2H3 cells exhibited phosphorylation of NF-κB p-65 as well as upregulation of the Nrf2 and HO-1 signaling pathways. Collectively, our study has successfully identified a novel inhibitor called CSB-0914 that effectively regulates inflammatory responses. These reactions are primarily mediated by the interplay between NF-κB, Nrf2, and HO-1. The findings of this study provide support for the need to conduct more research on CSB-0914 with the aim of its development as a pharmaceutical agent for anti-inflammatory purposes. Communicated by Ramaswamy H. Sarma

Revealing defect-bound excitons in WS2 monolayer at room temperature by exploiting the transverse electric polarized wave supported by a Si3N4/Ag heterostructure

Abstract Two-dimensional (2D) transition metal dichalcogenide (TMDC) monolayers are promising materials for light-emitting devices due to their excellent electric and optical properties. However, defects are inevitably introduced in the fabrication of TMDC monolayers, significantly influencing their emission properties. Although photoluminescence (PL) is considered as an effective tool for investigating the defects in TMDC monolayers. However, the PL from the defect-bound excitons is revealed only at low temperatures. Here, we show that the PL from the defect-bound excitons in a WS2 monolayer can be effectively revealed at room temperature by exploiting the transverse electric polarized wave supported by a Si3N4/Ag heterostructure. It is revealed that the defect-bound excitons in all possible positions of the WS2 monolayer can be effectively excited by the TE wave with significantly enhanced in-plane electric field localized on the surface of the Si3N4 layer. In addition, the emission from defect-bound excitons can propagate to the collection point with small attenuation. More importantly, the exciton dynamics in the WS2 monolayer can be modified by the Si3N4/Ag heterostructure, allowing the simultaneous excitation of neutral excitons, charge excitons (trions), and defect-bound excitons in the WS2 monolayer attached on the Si3N4/Ag heterostructure. We inspect the PL spectra obtained at different positions and find that the relative intensity of defect-bound excitons depends on the collection position. We also examine the dependences of the PL intensity and bandwidth on the excitation power for the three types of excitons. It is found that they exhibit different behaviors from those observed in the optical measurements by using the traditional excitation method. Our findings suggest a new way for exciting and studying the dynamics of multi-excitons at room temperature and indicate the potential applications of the TE wave in probing the defects in TMDC monolayers.

A new type of supercontinuum generation in hexagonal lattice C6H6-core PCF with broadband and low-power pump

Most of the spectral bandwidths of previous publications are still limited by high input powers making them economically less than ideal. By using a benzene core (C6H6) photonic crystal fiber (PCF) as a new supercontinuum (SC) light source, it is possible to achieve a very large spectral broadening with hundreds of times lower peak power. Due to the change in the diameter of air holes in the first ring near the core, near-zero flattened dispersion, high nonlinearity and small attenuation can be achieved for spectral broadening. The structural geometries of two C6H6-PCFs are optimized to generate wide SC at low input energy. The SC spectrum produced in 1[Formula: see text]cm long of all dispersion fiber extends from a part of visible light to the near-infrared range at 1.3[Formula: see text][Formula: see text]m wavelength and a small pulse energy of 18[Formula: see text]pJ (or 450[Formula: see text]W of electrical input). The second PCF shows wide soliton-induced SC from 0.8 to 4.2[Formula: see text][Formula: see text]m with 71[Formula: see text]pJ pulse energy (or input power approximately 790[Formula: see text]W) at 1.5[Formula: see text][Formula: see text]m wavelength within a fiber of 12[Formula: see text]cm. The proposed structures have the potential to become a new class of microstructured optical fibers for low-cost, broad-spectrum SC generation.

Perforated Concave Earplug (pCEP): A Proof-of-Concept Earplug to Improve Sound Localization without Compromising Noise Attenuation.

Combat soldiers are currently faced with using a hearing-protection device (HPD) at the cost of adequately detecting critical signals impacting mission success. The current study tested the performance of the Perforated-Concave-Earplug (pCEP), a proof-of-concept passive HPD consisting of a concave bowl-like rigid structure attached to a commercial roll-down earplug, designed to improve sound localization with minimal compromising of noise attenuation. Primarily intended for combat/military training settings, our aim was an evaluation of localization of relevant sound sources (single/multiple gunfire, continuous noise, spoken word) compared to 3M™-Combat-Arms™4.1 earplugs in open-mode and 3M™-E-A-R™-Classic™ earplugs. Ninety normal-hearing participants, aged 20-35 years, were asked to localize stimuli delivered from monitors evenly distributed around them in no-HPD and with-HPD conditions. The results showed (1) localization abilities worsened using HPDs; (2) the spoken word was localized less accurately than other stimuli; (3) mean root mean square errors (RMSEs) were largest for stimuli emanating from rear monitors; and (4) localization abilities corresponded to HPD attenuation levels (largest attenuation and mean RMSE: 3M™-E-A-R™-Classic™; smallest attenuation and mean RMSE: 3M™-Combat-Arms™4.1; pCEP was mid-range on both). These findings suggest that the pCEP may benefit in military settings by providing improved sound localization relative to 3M™ E-A-R™-Classic™ and higher attenuation relative to 3M™-Combat Arms™-4.1, recommending its use in noisy environments.

Semi‐Metallic Superionic Layers Suppressing Voltage Fading of Li‐Rich Layered Oxide Towards Superior‐Stable Li‐Ion Batteries

AbstractLi‐rich layered oxides (LRLOs) with greater specific capacity density are constrained by voltage attenuation and inferior rate performance because of irreversible oxygen release, metal dissolving and poor lithium‐ion transport capacity. Herein, a simple surface modification is designed to solve the performance degradation and structural collapse of LRLOs. Combining experiments with density functional theory (DFT) calculations, a semi‐metallic LiMn2O4‐like structure (LMO) with spin‐polarized conducting electrons, is introduced to the surface of the cathode restrains the activated surficial lattice oxygen ions by its stable oxygen vacancies. Additionally, Ni doping results in a fast‐ion conductor Li0.8Nb0.96Ni0.2O3 structure (LNO) with lowered lithium ions diffusion barrier, which is tightly conjugating to substrate and synergistically reinforces the Li diffusion path through the cathode‐electrolyte interphase. Moreover, Mn dissolution is successfully relieved due to the decrease in Mn concentration in the coating layers. As a result, the modified material (LRLO@LMO@LNO) exhibits an ultra‐high discharge capacity of 120.4 mAh g−1 even at 10 C with a very small discharge voltage attenuation of 313 mV after 600 cycles (0.52 mV per cycle) at 1 C. Undoubtedly, this method discloses a simple and effective approach to promote the practical utilization of high‐energy‐density.

Semi-Metallic Superionic Layers Suppressing Voltage Fading of Li-Rich Layered Oxide Towards Superior-Stable Li-Ion Batteries.

Li-rich layered oxides (LRLOs) with greater specific capacity density are constrained by voltage attenuation and inferior rate performance because of irreversible oxygen release, metal dissolving and poor lithium-ion transport capacity. Herein, a simple surface modification is designed to solve the performance degradation and structural collapse of LRLOs. Combining experiments with density functional theory (DFT) calculations, a semi-metallic LiMn2 O4 -like structure (LMO) with spin-polarized conducting electrons, is introduced to the surface of the cathode restrains the activated surficial lattice oxygen ions by its stable oxygen vacancies. Additionally, Ni doping results in a fast-ion conductor Li0.8 Nb0.96 Ni0.2 O3 structure (LNO) with lowered lithium ions diffusion barrier, which is tightly conjugating to substrate and synergistically reinforces the Li diffusion path through the cathode-electrolyte interphase. Moreover, Mn dissolution is successfully relieved due to the decrease in Mn concentration in the coating layers. As a result, the modified material (LRLO@LMO@LNO) exhibits an ultra-high discharge capacity of 120.4 mAh g-1 even at 10 C with a very small discharge voltage attenuation of 313 mV after 600 cycles (0.52 mV per cycle) at 1 C. Undoubtedly, this method discloses a simple and effective approach to promote the practical utilization of high-energy-density.

Effect of Wearing Different Masks on Acoustic, Aerodynamic, and Formant Parameters

This study aimed to investigate the effects of different types of masks on acoustic, aerodynamic, and formant parameters in healthy people. Our study involved 30 healthy participants, 15 of each gender, aged 20-40 years. The tests were conducted under four conditions: without a mask, after wearing a surgical mask, after wearing a head-mounted N95 mask, and after wearing an ear-mounted N95 mask. Voice recording was done with the mask on. The acoustic parameters include mean fundamental frequency (F0), mean intensity, percentage of jitter (local), percentage of shimmer (local), mean noise to harmonic ratio (NHR), aerodynamic parameter, maximum phonation time (MPT), and formant parameters (/a/, /i/, /u/ three vowels F1, F2). The main effect of mask type was significant in MPT, mean F0, mean HNR, /a/F1, /a/F2, /i/F2. However, the effect sizes and power in /a/F2, /i/F2 were low. MPT, mean F0 and mean HNR significantly increased and /a/F1 significantly decreased after wearing the head-mounted n95 mask. The mean F0 and mean HNR increased significantly after wearing the ear-mounted n95 mask. No significant changes were observed in parameters after wearing the surgical mask in this study. When the statistics are performed separately for males and females, the results obtained are similar to those previously obtained for unspecified males and females. After wearing the surgical mask, this study found insignificant changes in mean F0, jitter (local), shimmer (local), mean NHR, mean intensity, MPT, and the vowels F1 and F2. This may be due to the looser design of the surgical mask and the relatively small attenuation of sound. N95 masks have a greater effect on vocalization than surgical masks and may cause changes in F0 and HNR after wearing an N95 mask. In the present study, no significant changes in jitter and shimmer were observed after wearing the mask. In addition, there was a significant reduction in /a/F1 after wearing the N95 headgear mask may owing to its high restriction of jaw mobility. In future studies, the change in jaw movement amplitude after wearing the mouthpiece can be added to investigate.

A Method of Quantitative Detection of Fatigue Crack Depth in Bottom Rails by Ultrasonic Guided Waves Based on PCA-SVM

Abstract Ultrasonic guided wave is widely used to detect cracks in rail because of its long propagation distance and small attenuation. To effectively detect the fatigue crack in rail bottom through ultrasonic guided wave, an improved principal component analysis-support vector machine (PCA-SVM) intelligent algorithm based on grid search (GS) is proposed to detect the fatigue crack at different depths of rail bottom. The finite element method is used to establish the model of ultrasonic guided wave at different depths of the rail bottom, and the simulation model is compared with the experimental data to determine the effectiveness of the simulation model. Five main component features of the fatigue cracks at different depths are extracted by PCA. The GS method is used to optimize the penalty factor c and kernel function parameter g in the SVM, and the optimized SVM model is selected to identify the rail fatigue crack at different depths. The combination of theoretical simulation and experimental results shows that the accuracy of the training set and the test set of the improved PCA-SVM intelligent algorithm based on the GS method can reach 99.79 % and 99.73 %, respectively, which provides a basis and method for the detection of the fatigue crack depth of the rail bottom.

A 7-nm FinFET 1.2-TB/s/mm2 3D-Stacked SRAM Module With 0.7-pJ/b Inductive Coupling Interface Using Over-SRAM Coil and Manchester-Encoded Synchronous Transceiver

A 0.7-pJ/bit, 8.5-Gb/s/link inductive coupling interchip wireless communication interface for a 3D-stacked static-random access memory (SRAM) has been developed in a 7-nm FinFET process. A new physical placement method that allows coils to be placed over off-the-shelf SRAM macros with small magnetic field attenuation, together with the use of synchronous communication using Manchester encoding and a clocked comparator to enable the detection of small-swing signals, achieves a 26% reduction in SRAM die area compared to through-silicon via (TSV)-based stacking. Interchip communication at 0.7 pJ/bit, 8.5 Gb/s/link was confirmed using test chips. A 4-hi 3D-stacked SRAM module using the proposed interface achieves a 1.2-TB/s/mm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{2}$</tex-math> </inline-formula> area efficiency, representing a two orders-of-magnitude improvement over the state-of-the-art 3D-stacked SRAM.

Optimization of Dispersions in GeO2-doped Photonic Crystal Fibers with Square Lattice

Germanium doped photonic crystal fibers with differences in the layers' air hole diameters in the cladding are presented to obtain flat dispersion, small effective mode area, and low attenuation property for supercontinuum generation applications. The flatness and small value of the dispersion depend on the lattice geometry when the fibers have the same germanium doping concentration. The dispersion of the square lattice fibers is a flatter and smaller value at the pump wavelength than the circular lattice fibers. Square lattice fibers with Ʌ = 0.9 µm, d1/Ʌ = 0.4 and Ʌ = 1.0 µm, d1/Ʌ = 0.45 are proposed for supercontinuum generation which has anomalous and all-normal dispersion, respectively. Their small dispersion values of 0.449 ps /nm.km and −1.096 ps/nm.km are suitable for broad spectrum supercontinuum generation. The small effective mode area and low attenuation of the two fibers of 3.221 µm2, 2.361 µm2 and 1.805×10−7 dB/m, 1.322×10−15 dB/m, respectively are favorable conditions for choosing a laser pump sources with low peak power. The proposed fibers can be new supercontinuum generation source replacing traditional glass core fibers.

Eulerian-Eulerian Modeling of the Features of Mean and Fluctuational Flow Structure and Dispersed Phase Motion in Axisymmetric Round Two-Phase Jets

The features of the local mean and fluctuational flow structure, carrier phase turbulence and the propagation of the dispersed phase in the bubbly and droplet-laden isothermal round polydispersed jets were numerically simulated. The dynamics of the polydispersed phase is predicted using the Eulerian–Eulerian two-fluid approach. Turbulence of the carrier phase is described using the second-moment closure while taking into account the presence of the dispersed phase. The numerical analysis was performed in a wide range of variation of dispersed phase diameter at the inlet and particle-to-fluid density ratio (from gas flow laden with water droplets to carrier fluid flow laden with gas bubbles). An increase in the concentration of air bubbles and their size leads to jet expansion (as compared to a single-phase jet up to 40%), which indicates an increase in the intensity of the process of turbulent mixing with the surrounding space. However, this makes the gas-droplet jet narrower (up to 15%) and with a longer range in comparison with a single-phase flow. The addition of finely dispersed liquid droplets to an air jet suppresses gas phase turbulence (up to 15%). In a bubbly jet, it is found that small bubbles (Stk &lt; 0.1) accumulate near the jet axis in the initial cross-sections, while concentration of the large ones (Stk &gt; 0.2) along the jet axis decreases rapidly. In the gas-droplet jet, the effect of dispersed phase accumulation is also observed in the initial cross-section, and then its concentration decreases gradually along the jet axis. For gas bubbles (Stk &lt; 0.1), small turbulence attenuation (up to 6%) is shown.