We propose a wide-field absolute transverse blood flow velocity measurement method in vessel centerline based on absorption intensity fluctuation modulation effect. The difference between the light absorption capacities of red blood cells and background tissue under low-coherence illumination is utilized to realize the instantaneous and average wide-field optical angiography images. The absolute fuzzy connection algorithm is used for vessel centerline extraction from the average wide-field optical angiography. The absolute transverse velocity in the vessel centerline is then measured by a cross-correlation analysis according to instantaneous modulation depth signal. The proposed method promises to contribute to the treatment of diseases, such as those related to anemia or thrombosis.
With the advantages of wide range, non-contact and high flexibility, the visual estimation technology of target pose has been widely applied in modern industry, robot guidance and other engineering practices. However, due to the influence of complicated industrial environment, outside interference factors, lack of object characteristics, restrictions of camera and other limitations, the visual estimation technology of target pose is still faced with many challenges. Focusing on the above problems, a pose estimation method of the industrial objects is developed based on 3D models of targets. By matching the extracted shape characteristics of objects with the priori 3D model database of targets, the method realizes the recognition of target. Thus a pose estimation of objects can be determined based on the monocular vision measuring model. The experimental results show that this method can be implemented to estimate the position of rigid objects based on poor images information, and provides guiding basis for the operation of the industrial robot.
In order to improve the engine vibration signal process method for the engine cylinder pressure and engine revolution speed measurement instrument, the engine cylinder pressure varying with the engine working cycle process has been regarded as the main exciting force for the engine block forced vibration. The forced vibration caused by the engine cylinder pressure presents as a low frequency waveform which varies with the cylinder pressure synchronously and steadily in time domain and presents as low frequency high energy discrete humorous spectrum lines in frequency domain. The engine cylinder pressure and the rotation speed can been extract form the measured engine block vibration signal by low-pass filtering analysis in time domain or by FFT analysis in frequency domain, the low-pass filtering analysis in time domain is not only suitable for the engine in uniform revolution condition but also suitable for the engine in uneven revolution condition. That provides a practical and convenient way to design motor revolution rate and cylinder pressure measurement instrument.
In order to get electroluminescent devices incorporate high efficiency, easy fabrication and long-term physical stability, single layer electroluminescent devices based on soluble p-type polymer PDDOPV [poly (2,5-bis (dodecyloxy)-phenylenevinylene)] doped by n-type soluble polymer PPQ [poly (phenyl quinoxaline)] are successfully fabricated. Compared with single layer device of pure PDDOPV, the turn-on voltage of doped single layer devices is drop from 4.5V to 2.6V, at the same applied voltage, the current is higher but still at the same order of magnitude, the brightness and luminescent efficiency are both enhanced more than one order of magnitude. At 10 V, the current, brightness and luminescent efficiency of devices of blends are 1.95, 30.9 and 16 times of those of devices of pure PDDOPV respectively. The remarkable enhancement of doped devices is attributed to the reduction of injection barrier of minority carrier and enhancement of minority carrier injection caused by the doping PPQ in PDDOPV. This result demonstrates that it is an effective way to improve the device performance by doping n-type polymer in p-type polymer.
Since the initial discovery of electroluminescence in PPV [poly (p-phenylenevinylene)], polymer light emitting devices have been widely investigated. Aiming at overcoming the lack of electron type polymer can be used in polymer electroluminescent devices, using n-type semiconducting inorganic material ZnO:Zn as electron transport layer and p-type semiconducting polymer PDDOPV as hole transport layer, device based on heterojunction with structure ITO/PDDOPV/ZnO:Zn/Al is successfully fabricated. The highest ratio luminescent efficiency of heterojunction device to that of single layer device of PDDOPV is 38.6 times at 8V, the brightness and current of heterojunction device are 19.4 times and 0.5 time of that of single layer device respectively. The results demonstrate that the insertion of ZnO:Zn layer can transport electrons and block holes that lead to the decrease of current and increase of luminescent brightness and efficiency. The electroluminescent spectra of single layer device were bias-independent while that of heterojunction device were bias-dependent. The emitting color of single layer device is orange, while that of heterojunction device shifts from orange to green-yellow and finally becomes green as the applied voltage increases. The full width at half maximum (FWHM) of single layer device is 50 nm, while that of heterojunction device is from 70 to 84 nm. Different photoluminescent spectra of heterojunction device are obtained at different excitation wavelength. Exciplex theory is often used to explain the origin of new emitting color, but it is not suitable here because exciplex emission should leads to red-shift emission. We attribute this phenomenon to the conformation of new light-emitting unit.
Organic light emitting devices (OLEDs) have attracted great interest because of their bright future as a competitive flat-panel display technique of LCD. OLEDs based on PDDOPV [poly (2,5-bis (dodecyloxy)-phenylenevinylene)]/Alq3 (8-hydroxyquinoline aluminum) heterostructure were fabricated. The emission spectrum of the device base on heterostructure PDDOPV(70nm)/Alq3(20nm) is similar to that of single layer device of PDDOPV except the emission intensity is enhanced by several magnitude order. But the emission spectrum of the device based on heterostructure PDDOPV(70nm)/Alq3(32nm) is composed of two parts, one is originated from PDDOPV , the other is from Alq3. The emission from PDDOPV dominates at low drive voltage but the contribution from alq3 emission increases with the increase of applied voltage. Finally ,Alq3 emission dominates at high applied voltage.
Alternating current polymer light emitting devices (PLEDs) have attracted much attention because ac operation can partially reverse electrochemical reaction at interfaces and a longer lifetime is expected over dc operation. Most ac PLEDs to date are based on symmetrical structure. Here novel alternating current EL devices with asymmetric structure are successfully fabricated by using a hole type polymer PDDOPV [poly (2,5-bis (dodecyloxy)-phenylenevinylene)] and an electron type polymer PPQ [poly (phenyl quinoxaline)]. Two devices with following structure were made, Device 1: ITO/PDDOPV(70nm)/PPQ(40nm)/Al, Device 2: ITO/PDDOPV(100nm)/PPQ(70nm)/Al. Both devices can be operated at forward and reverse dc bias and ac modes but the performance of Device 1 is much better than that of Device 2. Emitting intensity of both devices at forward dc bias was several magnitude orders stronger than that at reverse dc bias. Both the highest luminescent intensity and efficiency of Device 1 at ac operation were the same magnitude order as those at dc operation, but those of Device 2 at ac operation were about 1 magnitude order higher than those at dc operation. Contribution from PPQ increases with the increase of applied voltage.
Most ac polymer EL devices to date are based on symmetrical structure. Here novel alternating current EL devices with asymmetric structure are successfully fabricated by using a hole type polymer PDDOPV and an electron type polyer PPQ. We report that performance of polymer devices with heterojunction under ac operation is not so sensitive to thickness of the two polymer layers as udner dc operation. This new advantage of ac operation mode over dc operation mode means easy production and cheap production facility in large-scale production in the near future. DIfferent emission spectra are obtained when our ac devices are operated in ac mode, forward and reverse bias. Emission spectrum at reverse bias includes two parts; one is from PPDOPV, the other from PPQ.
We report our research work and experiments on poly[(2,5- bis(dodecyloxy)-phenylenevinylene)-co-p-phenylenevinylene] P(DDOPV-co-PV) in detail. Our results demonstrate that the R (mol ratio) of DDOPV(2,5-bis(dodecyloxy)-phenylenevinylene) and PV determines the spectra of their copolymers in some degree. We give a half quantity explanation from so-called `free electron gas model' theory.