中国科学院机构知识库网格系统: 检索

Evolutionary characteristics and driving factors of carbon emission performance at the city level in China 期刊论文 OAI收割
SCIENCE CHINA-EARTH SCIENCES, 2022, 页码: 16
作者: Wang, Shaojian; Wang, Zehong; Fang, Chuanglin

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收藏 | 浏览/下载：20/0 | 提交时间：2022/09/21

Carbon emission performance at the city level Evolution characteristics Regional difference Influencing factors

Evolutionary characteristics and driving factors of carbon emission performance at the city level in China 期刊论文 OAI收割
SCIENCE CHINA-EARTH SCIENCES, 2022, 页码: 16
作者: Wang, Shaojian; Wang, Zehong; Fang, Chuanglin

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收藏 | 浏览/下载：13/0 | 提交时间：2022/09/21

Carbon emission performance at the city level Evolution characteristics Regional difference Influencing factors

Theoretical analysis of emission characteristics of second-order distributed feedback semiconductor lasers (EI CONFERENCE) 会议论文 OAI收割
Semiconductor Lasers and Applications IV, October 18, 2010 - October 19, 2010, Beijing, China
作者: Liu Y.; Liu Y.; Qin L.; Liu Y.; Wang L.

收藏 | 浏览/下载：29/0 | 提交时间：2013/03/25

Based on the modified coupled-wave theory the emission characteristics including threshold gain photon density distribution in the cavity and external differential quantum efficiency for second-order DFB lasers are investigated. Numerical simulation results show that for given device structure with wavelength of 1.55 m the feedback coupling coefficient and the surface radiation coupling coefficient of the second-order grating have great influence on the emission characteristics of the device. By choosing different duty cycles of the grating we can change the two coupling coefficients which affect the emission characteristics. For an overall consideration an optimal duty cycle of 0.43 is chosen. The optimized results show that the device works without degeneracy modes and spatial burning hole. Besides the side-mode suppress ratio (SMSR) and external differential quantum efficiency reach as high as 42 dB and 47% respectively. 2010 SPIE.

Temperature characteristics of high power vertical cavity surface emitting lasers (EI CONFERENCE) 会议论文 OAI收割
Semiconductor Lasers and Applications III, November 12, 2007 - November 13, 2007, Beijing, China
作者: Qin L.

收藏 | 浏览/下载：30/0 | 提交时间：2013/03/25

By using oxidation confinement technology high power vertical-cavity surface-emitting lasers are fabricated in experiment. The electrical and optical performance characteristics such as threshold current efficiency emission wavelength and output power are measured under continuous wave (CW) condition at room temperature. The maximum output power is up to watt regime at wavelength of about 980nm. The temperature characteristics of the device are investigated experimentally in detail. The variation in lasing threshold current with temperature is studied. The characteristic temperature T0 of the device is derived and the value is about 211K. Such a high characteristic temperature T0 of threshold current can lead to good temperature sensitivity of the device. At the same time the lasing spectrum characteristics with temperature are also measured. The wavelength shift with temperature is just about 0.06nm/K. From the measured results it is shown that the device can still operate at high temperature condition.

The synthesis and field emission property of carbon nanotubes on carbon fibers substrate (EI CONFERENCE) 会议论文 OAI收割
Technical Digest of the 20th International Vacuum Nanoelectronics Conference, IVNC 07, July 8, 2008 - July 12, 2008, Chicago, IL, United states
Leyong Z.; Weibiao W.; Jingqiu L.; Yuxue X.; Da L.; Song C.; Haifeng Z.

收藏 | 浏览/下载：34/0 | 提交时间：2013/03/25

Using ferrocene as catalyst precursor C2H2 as carbon source carbon nanotubes (CNTs) with uniform density were synthesized on carbon fibers substrate by floating catalyst method. The morphology and microstructure were characterized by field emission scanning electron microscope (FESEM) and high-resolution transmission electron microscopy (HRTEM). The observation showed that the length of CNTs is about 2 m the average space between adjacent CNTs is about 300 nm and the diameter of CNT is about 45 nm. The less dense "short and stubby" aligned CNTs films should have good electron field emission characteristics. The results of field emission showed that the emission current of CNTs/carbon fibers was 5 A at the field of 2.5 V/m and the emission current can be 280 A with a field of 7 V/m (the specimen area is 0.25 cm2 and the distance between cathode and anode is 200 m). The calculation based on the F-N plot indicated that the field enhancement factor of CNTs tip is 499122. Using the conductivity and chemical stability of carbon fibers and the uniform and sparse density distribution of CNTs on carbon fibers substrate the tip predominance of carbon nanotubes can be exerted and simultaneously the effect of screening effects between adjacent carbon nanotubes on the field emission performance can also be effectively decreased. The CNTs synthesized on carbon fibers substrate has many predominances for the fabrication of cold cathode devices. For example using the removability of carbon fibers the cathode of CNTs/carbon fibers can be arbitrarily moved enlaced or combined to form different patterns and the cathode of CNTs/carbon fibers can be also fabricated in large size. Therefore CNTs/carbon fibers may have potential application in field emission displays.

Low threshold field electron emission of diamond films (EI CONFERENCE) 会议论文 OAI收割
ICO20: Display Devices and Systems, August 21, 2005 - August 26, 2005, Changchun, China
作者:

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Since CVD diamond film possesses desirable properties it has been widely investigated and much research has been made in this field. In this experiment we mainly studied the characteristics of field emission from the CVD diamond films. The motivation for the experiment is to gain some insight into a possible emission mechanism. The diamond films are grown using a hot filament chemical vapor deposition basing on the diamond micro-grits on silicon substrates. And the diamond micro-grits are deposited on silicon substrates using electrophoresis coat method through a solution of diamond micro-grits in ethyl alcohol. This study has revealed that emission can be obtained at fields as low as 1.8V/m. And the field emission measurements were carried out at a pressure of 10-4Pa.

High-power InGaAs/GaAs VCSEL's two-dimension arrays (EI CONFERENCE) 会议论文 OAI收割
ICO20: Lasers and Laser Technologies, August 21, 2005 - August 26, 2005, Changchun, China
作者: Liu Y.; Wang L.-J.; Wang L.-J.; Liu Y.; Liu Y.

收藏 | 浏览/下载：27/0 | 提交时间：2013/03/25

Selectively oxidized InGaAs/GaAs vertical -cavity surface-emitting lasers (VCSEL) array at an emission wavelength of 980nm was reported. A 16 elements array with 200m aperture size (250m center spacing) of individual elements shows a CW output power of 1.21 W at room temperature resulting in 1 KW/cm2 average optical power density. The device threshold current is 1.32A The lasing peak wavelength is 981.9 nm the full width at half-maximum is 0.7 nm and the far-field divergence angle is about 17.The characteristics of a single device with a active region diameter of 800m is compared with that of a 2-D array with active region diameter of individual clement of 200m. These two kinds of devices have the same total lasing area. At the same current injection the single device has a higher threshold and a higher output power than the array. The red shift of single device is more obvious than that of the array's.

High power output and temperature characteristics of 1.06m diode array module (EI CONFERENCE) 会议论文 OAI收割
ICO20: Lasers and Laser Technologies, August 21, 2005 - August 26, 2005, Changchun, China
作者: Yao S.; Wang L.; Wang L.; Wang L.; Liu Y.

收藏 | 浏览/下载：63/0 | 提交时间：2013/03/25

In this paper high power diode array module with an emission wavelength of 1.06m is presented. The epitaxial structure is an InGaAs/GaAsP strained-compensated single-quantum well structure. Laser bars with a fill factor of 50% arc processed and show a good temperature characteristics with a slope efficiency only decreasing from 1.08W/A to 1.06W/A when the temperature of heat sink changes from 20C to 40C. The module's CW output power can reach to 68.5W at a current of 80A when the temperature of cooling water is 20C. The central wavelength is 1059.4nm.

Spontaneous emission and gain characteristics of InGaAs/InGaAsP quantum well laser (EI CONFERENCE) 会议论文 OAI收割
Optoelectronic Devices and Integration, November 8, 2004 - November 11, 2004, Beijing, China
作者: Wang L.; Wang L.; Wang L.

收藏 | 浏览/下载：18/0 | 提交时间：2013/03/25

Long wavelength InGaAs/InGaAsP multiple quantum well laser is grown by MOCVD. The characteristics of spontaneous emission amplified spontaneous emission and modal gain of the MQW is investigated by using single-pass multi-section technique. The amplified spontaneous emission is around a wavelength of 1500nm dependent on the temperature and the current density. The modal gain spectra show a red shift with increasing temperature. The peak modal gain exhibits a decrease with increasing temperature from 140K to 300K. The loss measurements shows that the main loss mechanism in the structure might be the free carrier absorption in the doped cladding layers and a internal modal loss of about 10cm-1.

AE signal processing and DSP implementation based on wavelet packet analysis (EI CONFERENCE) 会议论文 OAI收割
ICMIT 2005: Information Systems and Signal Processing, September 20, 2005 - September 23, 2005, Changchun, China
作者: Zhao J.; Wang K.

收藏 | 浏览/下载：15/0 | 提交时间：2013/03/25

To improve the accuracy of AE (Acoustic Emission) testing the wavelet packet analysis was introduced to process the AE signals. Extraction of the fault characteristic information would be influenced greatly if the faulted AE signal was not effectively denoised. Based on discussing the fast searching algorithm of BWPB (Best Wavelet Packet Basis) adopting Shannon entropy a new method based on BWPB was presented to denoise the AE signal from the faulted composite plate. Analyzing was performed on the denoised signal and the fault characteristic information was exacted. To improve the real-time performance of the wavelet packet analysis algorithm it was performed on the DSP (Digital Signal Processing) chip TMS320VC5409. The experimental results show that the algorithm can not only reduce the noise by 10dB but also effectively extract the faulted characteristics information from the AE signal.