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Droplet injection methods are widely used in the applications of microelectronic manufacturing, biological engineering, and 3-D printing. This work presents a new jet dispenser driven by a single piezoelectric stack that enables the capability of drop-on-demand patterning under a high working frequency (500 Hz). Due to the special designs of the jet dispenser, a broad range of liquids, whose viscosities span more than four orders of magnitude (21-665 320 cps), can be jetted. Moreover, a coupled Coulomb damping physical model is proposed, which includes an electromechanical and a dynamic model. Both the Coulomb and the fluid-solid damping are considered in the dynamic model. In order to validate the results obtained by using MATLAB/Simulink, the experiments were carried out. The injection performance of this jet dispenser has been tested by employing a self-made jetting platform. The minimum volume of a jetting droplet is about 14.4 nL with liquid wax. The error of volume uniformity among droplets does not exceed 8%, and the error of angle trajectory is about 0.17°. Furthermore, the versatility of the jet dispenser is demonstrated by printing liquid lubricant, food, glue, silver past, and a ceramic slurry in predefined patterns.

Warning and controlling the water invasion in water-driving gas reservoirs is significant because water invasion will seriously hamper well productivity and gas recovery. Unfortunately, there are few comprehensive methodologies to control water invasion. In this paper, firstly, a water invasion model of reservoir scale is established and verified. Then a new workflow for Warning and controlling the water invasion is developed by the numerical simulation method in this paper. This paper takes the water-gas ratio corresponding to the turning point of the water invasion rate as the water invasion identification signal. Then, the method of water control after water invasion is studied by turning off the perforation of the primary water production. Finally, the optimal water control scheme is obtained by comparing water and gas production. The results show that the reserve accuracy of the established water invasion model is 99%, and the model has a good pressure-fitting result. After studying the warning method of water invasion, it is found that the water-gas ratio of about 10-2 m3/104m3 is the signal of water breakthrough under the well produced at fixed production. The water-gas ratio in the range of 10-3 to 10-2 m3/104m3 signals water breakthrough in the well producing at a fixed pressure. The water-gas ratio as a signal of water breakthrough will increase with the increase of gas production rate and decrease with the fixed bottom hole pressure increase. The water-gas ratio chart of the early warning under the different producing models is drawn in this paper for applications in the field. A study of the water control method found that there will be a success in controlling the water cut after closing the perforation of the primary water production. Water production has been reduced by 90.9%, and gas production has been reduced by only 9.7% after using the technique in the field.

The Shortest Vector Problem and the computation of the tame kernel in algebraic K-theory are two different but very important problems, and up to now no one has found any manipulated relations between them. In this paper, we are successful for the first time to reduce the computation of tame kernel, in particular the computation of elements of the set C m , the key part in the method proposed by Tate, to the Shortest Vector Problem of some lattice. Then, with the help of PARI library we implement the above idea and develop a program for computing the tame kernels of the cyclotomic fields with class number 1, and as an example, by running the program we obtain the tame kernel of the cyclotomic field Q ( ζ 7 ) .

Due to the fast response, high precision and high working frequency, needle driven piezoelectric micro-jet devices have been applied in various industrial fields. The injection performance is important for the applications. The jetting velocity of the micro-droplets has a great influence on the ligament length and satellites. In this paper, the Fluent stimulation model of dynamic mesh motion has been established to simulate the jetting process. Meanwhile, the dependences of volume and jetting velocity of micro-droplets on input signal, including voltage, falling time, and fluid pressure, have been studied. The results show that the jetting velocity of micro-droplets can be changed and the volume is invariant by adjusting falling time, which can be used to guide the control of the needle driven piezoelectric micro-jet devices. Furthermore, the experimental system has been designed and the experiments show that the average minimum jetting velocity is about 0.724 m/s. The ligament length increases almost linearly with jetting velocity of the micro-droplets. And the optimal jetting velocity is less than 2.745 m/s, which cannot generate satellites.

Wind load of an external floating-roof tank is analyzed using large eddy simulation (LES). First, the governing equations and a LES solution procedure employing FLUENT software are presented. Subsequently, using two benchmark tank models, the accuracy of LES is examined and the advantages of LES over wind Reynolds-averaged Navier-Stokes (RANS) method in computing the unsteady wind loads and vortex structures around a tank are validated. Finally, using LES, the turbulent flows and wind loads around an external floating-roof tank at varying Reynolds numbers and liquid levels are analyzed. The DSM SGS model was found to have better accuracy when LES is applied to the tank flow. For an external floating-roof tank, the Reynolds number has little influence on the wind load at Re > 106, while the liquid level affects significantly both the wind loads on the tank and the vortex structures in the flow, and the wind pressure on the internal wall distributes more evenly than that on the external wall, due to the recirculation of the flow in the cavity above the roof. In all cases, the pressure on the external floating-roof tank oscillates apparently with time, which indicates the necessity of applying LES to the wind load analysis of tanks.

Materials jetting, known as one of the 3D printing technologies, is widely applied in microelectronics packaging, biology and ceramic 3D printing due to its ability to print multi-materials by drop-on-demand. However, most of the materials are power-law fluids in 3D printing applications, the generation of satellites during the jetting process and droplet spreading characteristics are unclear and they have a great effect on the quality of the printout. In this paper, a common electromechanical and fluid-solid coupling model of the jet dispenser and observation platform of the jetting process are established. This modeling method is also suitable for other needle-driven jet dispensers. A commercial UV resin is adopted to study the jetting process of power-law fluid. To reveal the mechanism of satellite generation, the effects of input signals (rising time and falling time) on the dynamic characteristics of the needle and the jetting process are analyzed. On the basis thereof, the effectiveness of the optimal control parameters is demonstrated to eliminate satellites. In addition, the simulation and experimental results show that the falling time and fluid pressure can be controlled to adjust the spreading diameter and height of the droplet. Subsequently, the minimum line width of 0.276 mm is successfully printed with a nozzle of 0.07 mm.

The stochastic simulation of fan deltas has always been one of the significant problems in the numerical simulation of reservoirs. As one of the important numerical simulation methods of fan deltas, multiple-point statistics (MPS) obtains the statistical characteristics through the patterns in the training image (TI) to perform simulation. However, due to the non-stationarity of the TI of fan deltas, the traditional MPS cannot extract the non-stationary characteristics of the TI smoothly. Besides, traditional MPS mainly relies on CPU-based simulation, and the extracted probability information cannot be reused during simulation since the information only stored in memory instead of files on the storage medium, making the simulation process quite time-consuming if multiple simulations are performed successively. Thanks to the powerful feature extraction capability brought by deep learning, the fan delta simulation possibly will be largely improved. The generative adversarial network (GAN) is an important deep learning method for image generation, but it suffers from the lengthy simulation time and needs large-quantity training samples. Some variants of GAN, such as the single-image GAN (SinGAN), were proposed to reduce the amount of training data when realizing GAN. Based on SinGAN, a stochastic simulation method of fan deltas using parallel multi-stage GAN is proposed in this paper, through which the structural characteristics of fan deltas are learned from a single image of TI, and the stochastic simulation process can be parallelized for acceleration without lowering the simulation quality.

BigBand is a technique for wideband spectrum sensing (WSS) that can capture gigahertz of sparse spectrum in real time by using shifted multiple channels without sampling the signal at GS/s. In this paper, we focus on enforcing BigBand with the proposed improved algorithm, namely, AD-BigBand, for efficient and robust computation. AD-BigBand converts the nonlinear process (locating frequency and computing the spectrum value) of sparse WSS into two steps of solving linear equations. In particular, we define an $r$ -degree frequency locator polynomial to rapidly locate nonzero frequencies. The computing complexity of the proposed method decreases from $O(K{\log ^2}K ({{{n\log K} \over K}})^{\log K})$ of shifted sampling based BigBand to $O(K{\log ^2}K)$ , where the $K$ -sparse signals of bandwitdth $n$ are subsampled with arithmetic time-shifted sensing channels. We implement AD-BigBand on a commercial four-channel acquisition card. Experimental results show that AD-BigBand improves the WSS capabilities and exhibits higher processing speed and lower error spectrum construction rate than BigBand, especially in the case of relative low signal-to-noise ratio.

The relations between the tame kernels and second regulators of a number field F Galois over Q , in particular the fields of degree 8 over Q , and of some of its subfields are investigated through the action of the Galois groups on the tame kernels. In the case of the number fields with Galois group D 2 p , a result of Browkin and Gangl is improved.

Wideband spectrum sensing plays a key role in cognitive radio. Detecting wideband signals accurately and efficiently at low SNR regimes has recently attracted much interest from the research community. In this paper, two novel wideband sensing methods are presented, sequential sensing using phase-rotated spectral correlation detector (PSCD) and binary sensing using PSCD, which take advantage of PSCD's detection performance at low SNRs. They are explained in detail with diagrams and pseudo codes. Detection performance of the proposed methods in terms of detection probability and false alarm probability are evaluated in additive white Gaussian noise (AWGN) environment. The time complexity of the methods is also analyzed. Simulated results indicate that our methods outperform the energy detector at low SNRs.

The inorganic solid electrolytes Li6.25-xAl0.25La3Zr2-xTaxO12 (LALZT) with various Ta contents (x) are synthesized using conventional solid-state reaction method at 1200 ​°C for different holding times. The effect of holding time and Al/Ta co-doping on the crystal structure, microstructure and ionic conductivity of the LALZT solid electrolytes is discussed. The LALZT powder with a fine particle size and narrow particle distribution is prepared by the high-energy ball milling. Suitable Al/Ta doping stabilizes the cubic phase and enhances the ionic conductivity of the LALZT. The short holding time is 6 ​h due to the equal ionic conductivity for the LALZT samples sintered for 6 ​h or 10 ​h by the solid-state reaction method. The highest ionic conductivity can be obtained for the optimized composition of Li5.85Al0.25La3Zr1.6Ta0.4O12. The excellent ionic conductivity indicates that Al/Ta co-doped LALZT could be a promising electrolyte candidate for all-solid-state Li-ion batteries in practical application.

Vortex-induced vibration (VIV) of a flexible splitter plate attached to a square cylinder in laminar flow is investigated using fluid–structure interaction (FSI) simulation. The Reynolds number based on the edge length of the square cylinder (L) is fixed at Re = 100, while the structural parameters of the plate are set as ρ p (density ratio) = 84.75, H/L (non-dimensional thickness) = 0.06, E (non-dimensional elastic modulus) = 5 × 1 0 3 ∼ 5 × 1 0 6 and l/L (non-dimensional length) = 0.5, 1 and 2, respectively. It is found that the bending rigidity and plate length have significant influences on the dynamic response of the plate, fluid loads on the cylinder–plate body and the vortex pattern in the flow field. At l/L = 0.5, the natural frequency of the plate does not intersect with the vortex shedding frequency in the parameter range considered; VIV of the flexible plate is negligible, and the fluid loads and flow pattern are similar to those in the case of a rigid plate. At l/L = 1, lock-in occurs when the first natural frequency approaches the vortex shedding frequency. In the lock-in regime, the vibrating frequency of the plate shifts to be commensurate with the first natural frequency, and the first-mode bending motion of large amplitude is observed, resulting in higher vortex shedding frequency and narrower vortex street in the wake. At l/L = 2, besides the first-natural-frequency lock-in, the off-centerline phenomenon and second-natural-frequency lock-in are also observed at low elastic modulus. In the off-centerline regime, the mean deflection of the splitter plate shifts to one side and a second-mode-like bending motion appears, which breaks the symmetry of the flow pattern and generates a non-zero mean lift. In the second-natural-frequency lock-in region, the plate vibration and fluid loads are also amplified. The model proposed could be taken as a benchmark for VIV of the flexible plate in laminar flow, and the results obtained are insightful to the design of FSI-based piezoelectric energy harvesters using flexible plates.

Clubroot caused by Plasmodiophora brassicae is an increasingly important soilborne disease in China. The host range of P. brassicae was investigated with 30 cruciferous plants, including 16 crop species, 9 ornamentals, and 5 weeds in field and pot-cultured conditions. In the field, 17 species from five genera produced visible galls, and these included radish, Capsella bursa-pastoris, Orychophragmus violaceus, Sinapis alba, and 13 Brassica crops. In pot-cultured conditions, an additional 13 plant species (11 genera) were determined to be hosts of P. brassicae. Five common weeds were found to be hosts of P. brassicae, including C. bursa-pastoris, Lepidium apetalum, Descurainia sophia, S. alba, and Thellungiella salsuginea. The infection of these plants was confirmed via polymerase chain reaction (PCR) with primers specific to P. brassicae. No galls were found on Matthiola incana roots in the field or in pots and no resting spores of P. brassicae were observed in M. incana roots, although P. brassicae was detected in M. incana roots via PCR. Microscopic examination revealed infection only in the root hairs of M. incana roots. These results suggested that M. incana was highly resistant to P. brassicae in China and could be developed as a bait crop. In total, 297 accessions of oilseed rape were tested in the field, and 3 accessions of Brassica napus and 1 accession of B. juncea were found to be highly resistant to clubroot disease. These resistant resources provide options for managing clubroot in P. brassicae-infested fields.

In this paper, the relations between p-ranks of the tame kernel and the ideal class group for a general number field are investigated. As a result, nearly all of Browkin's results about quadratic fields are generalized to those for general number fields. In particular, a p-rank formula between the tame kernel and the ideal class group for a totally real number field of odd degree is obtained when p is a Fermat prime. As an example, the case of cyclic quartic fields is considered in more details. More precisely, using the results on cyclic quartic fields, we give some results connecting the p-rank(K2OF) with the p-rank(Cl(OE)), where F is a cyclic quartic field and E is an appropriate subfield of F(ζp).

In this study, the microstructure, dielectric, piezoelectric and dc bias properties of the Bi-doped PZT (PZTB) multilayer piezoelectric actuators, have been discussed. The thickness of the dielectric monolayer was about 70 μm, and a relatively uniform distribution of the grain size was developed. The application of a large dc bias field resulted in a decrease in the dielectric constant and dielectric loss of the multilayer piezoelectric ceramics. The shift of the Curie temperature (Tc) towards a higher value and stabilized temperature-dependent dielectric properties were observed under the dc bias field. The increase in parameter γ suggested the enhancement of the degree of diffuseness of the phase transition. The large displacement reached 0.11% of the thickness of the multilayer piezoelectric ceramic under a low driving voltage of 150 V, indicating the potential of commercial applications of the studied multilayer piezoelectric actuators. This study provides specific experimental data to evaluate the practical application of the Bi-doped PZT multilayer piezoelectric actuators.

A new synthetic strategy has been developed to encapsulate Ag nanoparticles in heterogeneous catalysts to prevent their dropping and sintering. Ag nanoparticles with diameters about 5–10 nm were first supported on the porous silica bead. These were then covered with a fresh layer of titanium dioxide with the thickness about 5 nm. SEM and TEM images were used to confirm the success of each synthesis step, and the photocatalytic activity of the as-synthesized samples was evaluated by photocatalytic decolorization of Rhodamine B (Rh B) aqueous solution at ambient temperature under both UV and visible light irradiation. The resulting titanium dioxide encapsulated Ag nanoparticles exhibited an enhanced photocatalytic activity under both UV and visible light irradiation, this can be attributed to effective charge separation and light harvesting of the plasmonic silver nanoparticles decoration, even the reducing of the exciton recombination rate caused by the small grain size of anatase TiO 2 nanocrystals.

Graphene oxide (GO) encapsulated TiO 2 core/shell composite microspheres with enhanced photo-activity were synthesized through a series of green and direct chemical bonding reactions involved with dehydration condensation between TiO 2 and GO without any modified agents. The as-prepared samples were well characterized by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), micro-Raman spectrometer and Fourier transform infrared spectrometer (FTIR). The photocatalytic activity of the samples was evaluated by photocatalytic decolorization of Rhodamine B (Rh B) aqueous solution at ambient temperature under both UV and visible light irradiation. TEM measurements revealed that the diameter of the as-prepared TiO 2 @GO core/shell composite microsphere was about 850 nm, while the thickness of the shell is about 5–10 nm. The photocatalytic degradation results showed that the GO-encapsulated TiO 2 core/shell structures exhibited an enhanced photocatalytic and excellent recyclability property under the irradiation of UV and visible light for the degradation of Rh B.

The problem of expressing an element of K_2(F) in a more explicit form gives rise to many works. To avoid a restrictive condition in a work of Tate, Browkin considered cyclotomic elements as the candidate for the element with an explicit form. In this paper, we modify and change Browkin's conjecture about cyclotomic elements into more precise forms, in particular we introduce the conception of cyclotomic subgroup. In the rational function field cases, we determine completely the exact numbers of cyclotomic elements and cyclotomic subgroups contained in a subgroup generated by finitely many different cyclotomic elements, while in the number field cases, using Faltings' theorem on Mordell conjecture we prove that there exist subgroups generated by an infinite number of cyclotomic elements to the power of some prime, which contain no nontrivial cyclotomic elements.

Access control is one of the key mechanisms for cloud computing security. When it comes to being used in cloud computing environments, RBAC is more scalable and more suitable compared with traditional discretionary and mandatory access control models. A straightforward way is to extend RBAC from traditional fields to cloud computing environments. In this chapter, several extended role-based access control schemes are surveyed from basic extension, A-RBAC, and trust-based RBAC separately. Core techniques of the proposed schemes are detailed. Comparisons around the proposed schemes are analyzed.

Hot-water extracts were prepared from fresh tea leaves and fractionated by DEAE-cellulose DE-52 column chromatography to yield one unexplored polysaccharide-conjugate fraction TPC-L (tea polysaccharide conjugates). Chemical components, molecular weight and its distribution, water vapor sorption properties, zeta potentials and optical characteristics of TPC-L were investigated. As compared with injured cell group, the two dosages of TPC-L (150 and 300 μg/mL) were discovered to possess remarkably protective effect on human umbilical vein endothelial cells against impairments induced by high glucose in a dose-dependent manner (p < 0.05, p < 0.001, respectively). Compared with group NC (normal control), the ingestion of 40 mg/kg of TPC-L could significantly reduce blood glucose levels of normal mice ingesting starch, and significant difference of AUC (area under the curve of blood glucose) and ΔAUC (p < 0.05, p < 0.01) at the postprandial time point of 0.5 and 1.0 h were observed. The three dosages of TPC-L (10, 40 and 160 mg/kg) did not significantly lower postprandial blood glucose levels of normal mice ingesting glucose. TPC-L could improve starch tolerance to prevent impaired glucose tolerance (IGT) from developing into diabetes as well as protective effects on HUVE cells against impairments induced by high glucose It was suggested that TPC-L improved IGT through its capability of inhibition on digestive enzymes.

In trusted computing, remote attestation is an essential feature to determine the trustworthiness of a remote platform by analyzing its integrity. In this paper, we present a new paradigm that leverages clustering system call arguments for integrity measurement and reporting in remote attestation. The major contribution of this paper is two-folds: (1) We introduce a clustering process to characterize system call arguments. (2) We introduce model verification for efficient trust reporting. Our proposed technique is evaluated on a real world dataset extracted from a Linux System. The results show that different clustering algorithms can achieve different average accuracy while introduce low overheads.

In this paper, three typical definitions of cloud computing are listed. Security issues in cloud computing are analyzed. Novelties in cloud threat model, new problems and new research directions in cloud computing environment are also outlined.

In order to standardize the procedure of digital forensics, on the basis of the deep research on existing computer forensic models, a digital forensic model based on data fusion is proposed, which carries out time constraint and legal restriction in linear course control and forensic supervision to the whole forensic process. The establishment of political-legal and judicial certificate authority departments will bring about the mutual trust and recognition not only among the related departments but also between them and the court during the entire evidentiary process. Finally, the model system submits the evidence chain and the chain of forensic supervision to the court, which improves the legal effect of electronic evidence.