LD End-Pumped Nd:YAG InnoSlab Laser at 1319 nm

The 1319 nm lasers have important research value and application prospects in optical communications, biomedicine and nonlinear frequency conversion. Currently, there are few reports of high power 1319 nm continuous lasers with high beam quality. We have demonstrated a high output power, high beam quality 1319 nm continuous-wave laser by laser diode end-pumped Nd:YAG slab with a stable-unstable hybrid resonator. With a pumping power of 477 W, an output of 96.8 W was obtained with a slope efficiency of 26.5% and stability of 0.27%. A single wavelength laser operation at 1318.7 nm was demonstrated. At an output of 91.1 W, the beam quality factors M2 in stable and unstable directions were 2.95 and 1.88, respectively.

A Comparison on the Localization Performance of Static and Dynamic Binaural Ambisonics Reproduction with Different Order

Ambisonics is a series of spatial sound reproduction system based on spatial harmonics decomposition and each order approximation of sound field.Ambisonics signals are originally intended for loudspeakers reproduction.By using head-related transfer functions(HRTFs)filters,binaural Ambisonics converts the Ambisonics signals for static or dynamic headphone reproduction.In present work,the performances of static and dynamic binaural Ambisonics reproduction are evaluated and compared.The mean binaural pressure errors across target source directions are first analyzed.Then a virtual source localization experiment is conducted,and the localization performances are evaluated by analyzing the percentages of front-back and up-down confusion,the mean angle error and discreteness in the localization results.The results indicate that binaural Ambsonics reproduction with insufficiently high order(for example,5-10 order)is unable to recreate correct high-frequency magnitude spectra in binaural pressures,resulting in degradation in localization for static reproduction.Because dynamic localization cue is included,dynamic binaural Ambisoncis reproduction yields obviously better localization performance than static reproduction with the same order.Even a 3-order dynamic binaural Ambisoncis reproduction exhibits appropriate localizations performance.

Influence of the Number of Loudspeakers on the Timbre in Horizontal and Mixed-Order Ambisoncis Reproduction

Ambisonics is a series of flexible spatial sound reproduction systems based on spatial harmonics decomposition of sound field.Traditional horizontal and spatial Ambisonics reconstruct horizontal and spatial sound field with certain order of spatial harmonics,respectively.Both the Shannon-Nyquist spatial sampling frequency limit for accurately reconstructing sound field and the complexity of system increase with the increasing order of Ambisonics.Based on the fact that the horizontal localization resolution of human hearing is higher than vertical resolution,mixed-order Ambisonics(MOA)reconstructs horizontal sound field with higher order spatial harmonics,while reconstructs vertical sound field with lower order spatial harmonics,and thereby reaches a compromise between the perceptual performance and the complexity of system.For a given order horizontal Ambisoncis or MOA reproduction,the number of horizontal loudspeakers is flexible,providing that it exceeds some low limit.By using Moore’s revised loudness model,the present work analyzes the influence of the number of horizontal loudspeakers on timbre both in horizontal Ambisonics and MOA reproduction.The binaural loudness level spectra(BLLS)of Ambisoncis reproduction are calculated and then compared with those of target sound field.The results indicate that below the Shannon-Nyquist limit of spatial sampling,increasing the number of horizontal loudspeakers influence little on BLLS then timbre.Above the limit,however,the BLLS for Ambisoncis reproduction deviate from those of target sound field.The extent of deviation depends on both the direction of target sound field and the number of loudspeakers.Increasing the number of horizontal loudspeakers may increase the change of BLLS then timbre in some cases,but reduce the change in some other cases.For MOA,the influence of the number of horizontal loudspeakers on BLLS and timbre reduces when virtual source departs from horizontal plane to the high or low elevation.The subjective evaluation experiment also validates the analysis.

A novel reprocessable chloroprene rubber based on dynamic disulfide metathesis

For sustainable application of chloroprene rubber(CR),a new technology is developed by the vulcanization of CR using 2,2'-dithiodipyridine(DPD)as a cross-linking agent with the repro-cessing performance owing to disulfde metathesis.When DPD was incorporated into CR vulcanization,the Menschutkin reac-tion between allyl chloride group and pyridine group occurred with a maximum exothermic peak at 184°C.The number of effective cross-linking bond at o.5 phr DPD vulcanizate was higher than that at high DPD content.This vulcanizate showed high tensile strength(11.12 MPa)and elongation at break(1253±120%)owing to the exchangeable disulfide bond in the system.Under the catalysis of triphenylphosphine,the metathesis of disulfide compound was improved obviously,which endowed CR/DPD vulcanizates with good recyclability performance.Disulfide cross-linkage maintains its stability at low temperature,thus ensuring the mechanical stability of CR/DPD vulcanizate under the ambient conditions.Vulcanization and reprocessing of CR/DPD vulcanizate can be conducted with common industrial rubber processing equipment.Such reprocessable chloroprene rubber could have potential appli-cation in CR industry,also serve to significantly improve envir-onmental sustainability.

Reflectometric and interferometric fiber optic sensor's principles and applications

Fiber optic sensors have been widely used and studied in recent times. This paper presents operating principles and applications of fiber optic sensors namely reflectometric and interferometric fiber optic sensors. Majority of optical fiber sensors fall under these two broad categories. Both interferometric and reflectometric fiber optic sensors are becoming popular for their ease of use, flexibility, long distance sensing, and potentially noise free detection. Also, these sensors can easily be used in various applications such as structural health monitoring, perimeter intrusion detection, temperature monitoring, and other numerous applications. This paper broadly classifies fiber optic sensors into two subtypes. The paper further highlights different sensors based on their sensing resolution, range, spatial advantages, and applications.