Broadband

摘要： NMR spectra acquired with experiments using frequency-sweeps such as the wide-band uniform-rate smooth truncation(WURST)spin-echo and Carr-Purcell-Meiboom-Gill(CPMG)sequences cannot be absorptively phased by using only conventional zerothand first-order phase correction.Implementation of phase correction up to the secondorder is described for obtaining absorptive spectra,which have more desirable line shapes and noise properties than magnitude spectra.The relationship of the second-order phase to the parameters of frequency sweeps is derived.The second-order phasing in the frequency-domain is equivalent to a point spread in the time-domain signal.The application of second-order phase correction is demonstrated with a wideline 35Cl CPMG spikelet spectrum.

摘要： Wireless communication is one of the rapidly-growing elds of the communication industry.This continuous growth motivates the antenna community to design new radiating structures to meet the needs of the market.The 5G wireless communication has received a lot of attention from both academia and industry and signicant efforts have been made to improve different aspects,such as data rate,latency,mobility,reliability and QoS.Antenna design has received renewed attention in the last decade due to its potential applications in 5G,IoT,mmWave,and massive MIMO.This paper proposes a novel design of broadband antenna for 5G mmWave and optical communication networks.It is a hybrid structure that works for both spectrums and contains an absorption dielectric material with an electrical large size.A hybrid transmission line theory ray-tracing technique is proposed efcient and rapid simulation and optimization of the proposed antenna design.The operating frequency and wavelength of the proposed antenna are 28 GHz in the mmWave band and 1550 nm for the optical spectrum.The spatial frequency is 30 lp/mm when the contrast transfer function is reduced to 0.7 for the optical signal.The effective focal length and aperture are 816.86 and 200 mm.The half-power beamwidth is 3.29◦and the gain is 32.97 dBi for the mmWave band.Simulation results show that the proposed hybrid antenna can effectively be deployed simultaneously for both optical and mmWave 5G communication networks.

摘要： Laser-driven light sources(LDLS)have ultrahigh-brightness and broad wavelength range.They are ideal radiation sources for optical metrology tools for advanced process control in semiconductor manufacturing.LDLS sources,with their advantages of 170 nm to 2100 nm wavelength range,have been widely adopted and are being used in volume manufacturing for spectroscopic ellipsometry(SE),spectroscopic scatterometry(SS),and white light interferometry(WLI)applications.Such applications are used to measure critical dimensions(CD),overlay(OVL),and film thickness.

摘要： 据Broadband TV News报道,2016年,138个国家的付费电视营收(订阅费和PPV电影、电视剧收入)达到峰值2 050亿美元。到2024年,付费电视营收将下降14%,降至1770亿美元。付费电视用户数量虽然将在2010年至2024年间增长3.8亿,但营收将与2010年持平。

摘要： Two-dimensional(2D) atomic crystals,such as graphene,black phosphorus(BP) and transition metal dichalcogenides(TMDCs) are attractive for use in optoelectronic devices,due to their unique crystal structures and optical absorption properties.In this study,we fabricated BP/ReS2 van der Waals(vdWs) heterojunction devices.The devices realized broadband photoresponse from visible to near infrared(NIR)(400–1800 nm) with stable and repeatable photoswitch characteristics,and the photoresponsivity reached 1.8 mA/W at 1550 nm.In addition,the polarization sensitive detection in the visible to NIR spectrum(532–1750 nm) was demonstrated,and the photodetector showed a highly polarization sensitive photocurrent with an anisotropy ratio as high as 6.44 at 1064 nm.Our study shows that van der Waals heterojunction is an effective way to realize the broadband polarization sensitive photodetection,which is of great significance to the realization and application of multi-functional devices based on 2D vdWs heterostructures.

摘要： This study focuses on a noise emitted from a radial underexpanded jet. The underexpanded jet is well known as one of supersonic jets and it is formed when the pressure ratio across a convergent nozzle is more than the critical value. The underexpanded jet has been used in many fields, such a propulsion of rocket, laser cutting and a glass tempering process. Such jet is exhausted from a circular nozzle. The expansion wave, the compression wave and the shock wave are periodically formed in the jet, which leads to quasi-periodical shock-cell structure. On the other hand, an underexpanded jet radially issues from intake and exhaust valves of an internal combustion engine and a pressure control valve. The radial underexpanded jet does not have the quasi- periodical shock-cell structure such as the jet from the circular nozzle, its cell length decreasing along jet axis. In this study, an underexpanded jet radially discharged from a circular slit nozzle, which consists of two circular tubes, is experimentally examined for different nozzle pressure ratios. The jet structure is visualized using Schlieren method and a noise emitted from the jet is measured. Typically, the shock associated broadband noise is analyzed and a relation between the jet structure and the radiation noise frequency is discussed. As a result, it is found that the broadband noise lies on lower frequency than a screech tone and that the 1st cell length plays an important role in broadband noise radiation.

摘要： In order to improve the performance of the shaking table,a vibration-enhanced shaking table which exploited broadband resonance was constructed.The broadband resonance was realized by an adjustable stiffness mechanism which exploited gas compressibility.Different from the traditional device,a gas filled cylinder(GFC)was mounted between the shake table and the exciter,and a pressure regulator was designed to regulate the gas pressure of the GFC.The natural frequency of the designed shaking table can be adjusted based on the compressibility of gas during the test.The principle of stiffness adjustment was theoretically analyzed and a series of experiments were carried out to investigate the effects of regulating the natural frequency.The experimental results indicate that the amplitude can be twice amplified and the natural frequency can be regulated between 2 0 Hz and 6 0 Hz.

摘要： 据Dataxis数据,截至2017年底,亚洲拥有4K机顶盒的付费电视订户数量已达5 360万。逾30家付费电视运营商已在亚洲推出4K机顶盒。韩国IPTV运营商韩国电信、LGU Plus、SK Broadband以及Tbroad在2014年三季度推出了4K机顶盒,是首批推出4K机顶盒的运营商。此后,中国、泰国、日本、印尼、新西兰、越南和澳大利亚的运营商也陆续推出4K机顶盒。