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The stability and vibration characteristics of an axially moving plate in an aero-thermal environment subjected to transverse excitation are investigated. In the modeling of the equation of motion, the influences of the in-plane thermal load and the perturbation aerodynamic pressure on the transverse bending deflection of the axially moving plate are taken into account. The governing equation of the plate in aero-thermal environment is established applying the Hamilton's principle based on the von Karman nonlinear plate theory and linear potential flow theory. For the linear equation, the natural frequencies of the moving plate are analyzed by solving the generalized eigenvalue problem. The critical parameters of the moving velocity, flow velocity and temperature change for the divergence of the plate are obtained. For the nonlinear equation, the displacement time responses of the plate in different stability states subjected to transverse excitation are analyzed by numerical simulations. From the study, it can be seen that with the moving velocity, flow velocity and temperature change increasing, the fundamental natural frequency of the plate decreases. When the fundamental natural frequency decreases to 0, the plate is in a divergence type of instability. The critical moving velocity decreases with increasing flow velocities and temperature changes. The vibration amplitude of the plate in divergence state is larger than that in the stable state. The vibration amplitude increases with the flow velocity and temperature change increasing, which illustrates that the aero-thermal environment has significant effects on the stability and vibration properties of the axially moving plate. [ABSTRACT FROM AUTHOR]

In order to increase the muscovite/solution active regions in black shale during pressure acid leaching process, a novel reinforcing method is proposed: the hydrating and hardening of anhydrous calcium sulfate (CSA). By adopting this method, the vanadium extraction reached 95.45% after 5 h at a temperature of 150 °C with a sulfuric acid concentration of 20 vol% and potassium sulfate addition of 7 %wt. The addition of potassium sulfate accelerated the hydration of CSA to converts into calcium sulfate dihydrate (CSD). Under hydrothermal conditions, the CSD dissolved and crystallized to transform back into CSA. The transformation of CSD → CSA hardened CSA crystals and caused local stress and generated expension and cracking to muscovite particles. This produced more muscovite/solution active regions to make aluminum and vanadium ions exposed to the attack of hydrogen ions, prompting vanadium release from muscovite lattice. [ABSTRACT FROM AUTHOR]

The purpose of this study was to assess the differences in clinical and sonographic features of papillary thyroid carcinoma (PTC) between cervical lymph node metastatic (CLNM) and nonmetastatic groups. Clinical data of PTC patients (414 patients with 624 malignant nodules) who underwent a preoperative ultrasonography and surgery between June 2010 and March 2015 at Renmin Hospital of Wuhan University were retrospectively analyzed. Clinical factors, preoperative ultrasound features and the final pathological findings were obtained. The differences in the sonographic features of PTC between the CLNM group and the non-CLNM group were analyzed. There were 187 CLNM and 227 non-CLNM patients. The median age at the diagnosis of this cohort was 45.4 years old (ranging from 18 to 77 years). Ultrasonographic parameters that were significantly associated with CLNM [OR=2.569 (1.502, 4.393), P<0.001)] were as follows: the mulifocality of the nodules, size over 2 cm, the presence of microcalcifications, the distance ratio (DR) pattern showing the contact of the nodules with the thyroid capsule, and the extracapsular spread of the nodules. No significant differences in age, gender, thyroid stimulating hormone (TSH) levels and other ultrasonography parameters were found between the CLNM and the non-CLNM groups. Therefore, our results suggest that a larger size, microcalcifications, mulifocality, and the DR pattern showing the contact of the nodules with the thyroid capsule and extracapsular spread are significantly more indicative of CLNM in PTC. [ABSTRACT FROM AUTHOR]

In this paper, reliability analysis for dynamic structural system is presented to predict chatter vibration in a milling system. Chatter reliability is defined to represent the probability of stability (no chatter occurs) of milling system. Probability model (reliability model) of chatter vibration is established to predict milling chatter vibration, in which structural parameters and spindle speed are considered as random variables. Choosing chatter frequency as an intermediate variable, the reliability model is built. The first-order second-moment method is adopted to solve the reliability model of the milling process system to obtain the reliability level of the system. The reliability lobe diagram (RLD), which is a contour line with a specified reliability level as a function of spindle speed and cutting depth, is presented to designate the reliable region for chatter vibration prediction. A numerical example is used to demonstrate the method for reliability analysis. The reliability of milling chatter system was calculated using first-order second-moment (FOSM) method and compared to the Monte Carlo simulation method. The results from the FOSM method and Monte Carlo method were found to be similar. Comparing the results with the traditional stability lobe digram (SLD) method, chatter reliability of milling process system can be used to judge the probability of stability of milling process system. It can be concluded that RLD can be efficiently used to predict reliability in workshop applications. [ABSTRACT FROM AUTHOR]

The dynamics and stability of an axially moving plate interacting with surrounding axial airflow are investigated. The dynamic model of the axially moving plate is established based on the Kirchhoff-Love plate theory and the linear potential flow model. The natural frequencies of the plate under different moving velocities and airflow velocities are calculated by solving the generalized eigenvalue problems of the dynamic system, from which the stability of the plate is analyzed. The effects of the surrounding airflow and the length to width ratio of the plate on the critical divergence velocity and the flutter velocity are discussed. From the simulation, it can be seen that with the flow velocity increasing, the natural frequencies of the plate decrease and then couple, resulting in the plate losing stability of the divergence and flutter types. With the length to width ratio of the plate increasing, the critical divergence velocity and the flutter velocity of the plate decrease. The critical divergence velocity and flutter velocity of the plate in surrounding airflow are lower than those in vacuum, which indicates that it is necessary to consider the effects of the surrounding airflow when analyzing the stability of the axially moving plate. [ABSTRACT FROM AUTHOR]

A series of sulfobutyl ether β-Cyclodextrins (SBE-β-CDs) with specific average degree of substitution (DS) were successfully synthesized, using a three-step synthesis method, through the reaction between β-Cyclodextrin (β-CD) and 1, 4-butane sultone in the sodium hydroxide solution. Although the ratio of β-CD and 1, 4-butane sultone is a dominant factor affecting the average degree of substitution of products, a typical optimization on other synthesis parameters is also necessary to precisely obtain these products. The optimization includes the addition of sodium hydroxide solution, the range of pH and reaction time in different reaction stages. Actually, each product is a mixture with various degrees of substitution and different positional isomers. Under the optimal conditions, the average degree of substitution and the characterizations of SBE-β-CDs were investigated by means of FTIR, 1 H NMR, 13 C NMR, HRMS, Capillary Electrophoresis, DSC and HPLC. The results indicated that the substitution reaction occurred simultaneously on C 6 –OH and C 2 –OH in the moderate alkaline solution and the proportion of C 2 –OH substituted increased with the increase of DS. The DS of SBE-β-CDs had better reproducibility and the distribution of composition analyzed by capillary electrophoresis was a normal distribution. In the novel synthesis process, the yield of the products was significantly improved. For example, the yield of SBE 7 -β-CD reached up to 80%. Moreover, the DS of SBE 7 -β-CD was 6.68 and the purity of SBE 7 -β-CD was 96% in line with quality standards of United States Pharmacopeia. [ABSTRACT FROM AUTHOR]

The dissolution behavior of muscovite in stone coal during the oxygen pressure acid leaching process was studied. The study showed that the dissolution behaviors of V, Al, and K were similar. K was the most easily leached, followed by Al, and then by V during oxygen pressure acid leaching process. When the reaction temperature exceeded 423 K (150 °C), alunite was generated, which led to vanadium losses because of its absorption performance. The dissolution of the muscovite in stone coal mainly depended on HSO concentration and temperature. O had a main effect not on muscovite's dissolution but on the V oxidation. During the oxygen pressure acid leaching process, (1) the interfacial K in the muscovite lattice was dissolved rapidly, producing a new interface; (2) for charge balance, the interfacial O absorbed hydrogen ions to form hydroxy; (3) the interfacial hydroxy reacted with hydrogen ions and left vacancy as a result of O loss, producing more new surface to expose more Al, V, and Si; (4) the interfacial Al or V was exchanged by hydrogen ions and V was oxidized to V and V; and (5) Si hardly reacted with H and generated high-Si surface. [ABSTRACT FROM AUTHOR]