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One important characteristic of bubbly oil-in-water two-phase flows is the droplet size distribution, which has a significant effect on the heat/mass transfer between phases and the turbulence characteristics. In this study, a sampling device of dynamic fluid is designed to trap the morphological structures of the bubbly oil-in-water flows with low flow rate and high water cut. In the experiment, oil droplets in vertical upward pipe are forced into a sampling slot which is specifically designed to ensure that the passing oil droplets are not overlapped. The images of the oil droplets are recorded using a high speed camera when the mixture flows through the sampling slot. The methods of multi-scale edge detection and watershed segmentation are employed to extract the edges of the solitary and adjoining oil droplets in the flow images. Based on the detected oil droplet edges the equivalent oil droplet diameters are derived and compared with a model of maximum droplet diameter. Additionally, time-frequency entropy and the total energy of measured conductance signals are extracted using Adaptive Optimal Kernel Time-Frequency Representation (AOK TFR) to characterize the droplet size distribution of bubbly oil-water two-phase flows.

Aiming at the shortcomings of current permanent magnet synchronous motor control, such as electromagnetic torque pulsation, flux pulsation, poor anti-interference performance and slow response speed. This paper introduces the control method of high frequency injection optimization sliding mode permanent magnet synchronous motor. Through the establishment of PMSM vector mathematical model. The design is based on high frequency injection and optimized sliding mode controller, MATLAB/Simulink was used for modeling and simulation analysis. It turned out that Compared with the traditional high frequency injection method and sliding mode controller, the vector control of permanent magnet synchronous motor based on high frequency injection and optimized synovial controller has stronger anti-interference, better reduction of chattering, which can improve the characteristics of the system more effectively and meet the needs of actual motor control.

In this paper, a Simulation Research on Fault Diagnosis of CNC Machine Tools Based on Fuzzy Petri Net is proposed. According to the fault information of the CNC machine tool electrical system, the Petri net and fuzzy reasoning are combined to establish the fuzzy Petri net model of the CNC machine tool electrical system. Describes the relationship between CNC machine faults. The fuzzy generation rule is represented by FPN. The fault diagnosis rule of Petri net is used for fault diagnosis reasoning. A fuzzy Petri net model combining reverse reasoning and forward excitation is proposed to analyze the causal relationship between abnormal behavior processes. Combining the feasibility of the occurrence relationship between faults and the frequency of faults, reverse reasoning and forward excitation can accurately and quickly find the root cause of the fault, and can find the fault cause more quickly than the traditional fault diagnosis method. The maintenance time is reduced. The fault diagnosis of the electrical system of CNC machine tools is taken as an example. The diagnostic model based on fuzzy Petri net is established. The correctness of the model and the effectiveness of the algorithm are verified by simulation analysis. Improve the usability of CNC machine tools.

Conductivity methods are commonly used in two-phase flow measurement due to their high sensitivity to the conductivity contrast between both phases. In this study, a dual-sensor probe array is newly designed to measure the local parameters of vertical upward gas–liquid two-phase flows in a small inner diameter pipe. Firstly, the measurements of gas volume fraction and gas velocity profiles are conducted using the dual-sensor probe array. Then series of bubble chord lengths at different locations are derived based on the rising velocities of the bubbles, and are compared with a model of maximum bubble diameter. Additionally, based on the simultaneously measured signals from the dual-sensor probe array, the structures of multiple bubble groups are visualized using a technology of phase density image. In view of the existence of the multiple bubble groups, the transformation from bubble chord length distribution to bubble size distribution is conducted based on the decomposition of the multiple bubble groups in the chord length distribution, and the evolution characteristics of the bubble size distributions at the pipe cross section are investigated as the flow condition changing.

A new spiro[indoline–naphthaline]oxazine derivative, 12-methoxy-14,14-dimethyl-17-(piperidin-1-yl)-7,8,14,15a-tetrahydro-4bH-naphtho[1″,2″:5′,6′][1,4]oxazino[3′,2′:2,3][1,4]oxazino[4,3-a]indole (1), was successfully synthesized, and its structure was characterized by 1H NMR, 13C NMR, IR, HRMS and single-crystal X-ray diffraction method. X-ray diffraction indicates that benzene and naphthalene rings of compound 1 are almost perpendicular, and the piperidine ring at the 6′-C site is in a chair conformation. In the packing diagram, a couple of short intermolecular distances such as the intermolecular short contact are observed. The photochromic properties of compound 1 have been fully investigated in different solvents, it was found that it exhibited excellent photochromism properties in solvents.

Three aryl and three naphthylmethylene derivatives containing thiadiazole ring have been synthesized. The structures of target compounds were characterized on the basis of spectral (FT-IR, 1H NMR, and MS). The optical properties were detected using UV-vis absorption spectroscopy and fluorescence spectroscopy. The absorption spectra of 1a, 2a and 3a substituted by naphthylmethylene are primarily characterized by a peak around 284 nm originating from naphthalene, which is different from that of compounds 1b, 2b and 3b. Compared to 1a and 2a (separated by a saturable atomic cluster −CH2−), the maximum absorption wavelength of 1b and 2b takes on obvious red-shifted, which is from thiadiazole and benzene with more large conjugated system. The fluorescence intensity of 2-(4-aminobenzoyl) amide-5-naphthylmethylene-1,3,4-thiadiazole (3a) was significantly higher than that of 5-(4-aminobenzoyl)-1,3,4-thiadiazole (3b) due to the presence of naphthalene.

Asymmetric 2-p-nitrophenyl-5-naphthylmethylene-1,3,4-oxadiazole and 2-p-aminophenyl-5-naphthylmethylene-1,3,4-oxadiazole were synthesized and characterized by IR、1HNMR and MS analysis, and their optical properties were detected using UV-vis absorption spectroscopy and fluorescence spectroscopy. The existence of electron-withdrawing oxadiazole units causes a significant bathochromic shift of the UV absorption maximum. The largest UV-absorption peak of target compounds is in the range of 298-317 nm, and a new emission band at 402 nm is formed. The fluorescence intensity is gradually enhanced, which strengthens the intramolecular charge transfer effect between the electron-withdrawing oxadiazole and electron-donating aniline.

Three novel triphenylamine (TPA) derivatives having perfluorinated cyclopentenyl and benzo[b]thiophene unit are obtained from 4-bromo-N,N-diphenyl-2-methylbenzo[b]thiophen-5-amine. The new compounds are expected to find their use in thin film devices as charge transport materials and host organic light-emitting materials. It is found that the new compounds show relatively strong fluorescence either in solution or in solid state, and are amorphous due to a special conformation which is elucidated by the fine structure of 19F NMR. Molecular structure and properties of these compounds is characterized by 1H NMR, 13C NMR (broadband decoupled), ESI–HRMS, elemental analysis and thermal analysis (DSC). Fluorescent quantum yield in solution is measured using 9,10-diphenylanthrancene (DPA) as standard fluorescent substance.

5-Diarylamino-2-methylbenzo[b]thiophene was a new kind of triphenylamine-based charge-transporting material. For further modification of the compounds, bromination selectivity was studied through experiments and molecular simulation using Gaussian 09 program under B3LYP/6-311G (d, p) aided by Gaussian View 05 and Multiwfn Program. The results showed that bromination of 5-diarylamino-2-methyl-benzo[b]thiophene would occurred at an “abnormal” positions (4- and/or 4′-position) rather than at the “normal” position (3-position), which was different from those benzo[b]thiophene derivatives with simple 5-substitutes reported in literatures. The “abnormal” selectivity resulted from a special electron structure in which there was an “interfinger-like” frontier orbital or a special “non-planar” conjugated model. Electrons would be donated to the o - and p -positions of linked aromatic rings by this manner of electron delocalization, so that TPA unit rather than thiophene ring became the main factor in the selectivity, and reaction active energy at 4-position was lowest. The results were confirmed by the synthesis of three 4-Br and/or 4′-Br derivatives, compound 4 , 5 and 6 . Single crystal X-ray diffraction of compound 6 gave conclusive evidence on the abnormal selectivity.

Eight ionic liquid crystals containing a biphenyl ester-based rigid core modified by a 3-alkyl-imidazolium cation were synthesised and characterised. The length of the alkyl chain varied between n = 4–18 carbon atoms. Their thermotropic phase behaviour was investigated using X-ray diffraction (XRD) measurements, variable temperature small-angle X-ray scattering (SAXS), polarising optical microscopy (POM) and differential scanning calorimetry (DSC). The compounds show rich mesomorphism, such as SmA2 phase (for compound C18) and SmC2 phases (for compounds C12–C16). For the molecules containing long alkyl chains (n ≥ 12), a novel mesophase, the T′ phase, was seen which has a unique ‘sandwich-like layer’ structure. The T′ phase is different from the known T phase and is formed at room temperature. Based on XRD, SAXS, DSC and POM data, models for the formation of the T′ phase are proposed.