The crystal form of TiO₂ is a crucial focus of research on the photocatalytic degradation of gaseous pollutants by TiO₂-based composite photocatalysts. To explore the synergistic effect of mixed crystalline TiO₂ on gaseous organic-pollutant photocatalytic degradation, we synthesized a series of TiO₂ nanoparticles with controllable phase ratios. We explored the role of the TiO₂ phase ratio on the photocatalytic activity and degradation pathway in the photodegradation of 2-propanol (IPA). We estimated the crystallite size and crystal proportions of anatase and rutile by X-ray diffraction. We used the Brunauer–Emmett–Teller method to calculate the specific surface area and Fourier transform infrared spectroscopy to characterize the surface chemistry of the samples. Our results show the photocatalytic activities of pure anatase and the sample with 8.6% rutile to be much better than those of the samples with a phase junction and pure rutile. As such, anatase is the better option for the study of photodegradation design and preparation of gas-phase organic pollutants.

Isobaric vapor–liquid equilibrium (VLE) data for three binary systems, chlorobenzene + N,N-dimethylformamide, chlorobenzene + furfural, and chlorobenzene + benzaldehyde, were measured at 50.00 and 101.33 kPa using a modified Rose–Williams still. Gas chromatography was used to analyze the compositions of the samples and no azeotropic behavior was found. All of the measured VLE values were checked by the semi-empirical method proposed by Herington and the point-to-point Van Ness test method modified by Fredenslund. The experimental data were correlated by using the Wilson, the non-random two-liquid and universal quasi-chemical activity coefficient models. The corresponding parameters for the three models were obtained.

This study focuses on shape-controlled synthesis of gold nanoparticles, using the green reducing agent l-Tryptophan (l-Trp), which is non-toxic and eco-friendly. This specific agent was investigated to realize certain morphology controlling effects by changing the relative growth rates among various crystal planes. Experimental samples were characterized by transmission electron microscope, UV–Vis spectrophotometer and X-ray diffraction (XRD) for size and morphological information. The effects of the specific additives of PVP ((C₆H₉NO) _n), CTAB (C₁₆H₃₃(CH₃)₃NBr), and KBr were examined for their morphological control individually and synergistically in this system. Hexagonal gold nanoparticles were successfully obtained via the PVP/CTAB and PVP/KBr systems. Particular amounts of PVP/KBr produced various polyhedron structures, such as cubes, and others with triangular and rhombic straight-side cross sections.

Titanium silicate-1 (TS-1) was treated with a mixed alkaline of tetrapropyl ammonium hydroxide (TPAOH) and NaOH. It was characterized by XRD, nitrogen physical adsorption, SEM, FT-IR, UV–Vis and ICP-OES, and studied in propylene epoxidation. The mixed alkaline treatment with TPAOH/NaOH solution did not destroy the MFI structure of TS-1. With increasing NaOH concentrations, the relative crystallinity and the framework titanium decreased to some extent while the mesopore volume, mesopore diameter, and extra-framework titanium increased appreciably. When NaOH concentration was 0.0333 mol L⁻¹, the best catalytic performance was obtained.

This paper investigates the stability of the Francis hydro-turbine governing system with complex penstocks in the grid-connected mode. Firstly, a novel fractional-order nonlinear mathematical model of a Francis hydro-turbine governing system with complex penstocks is built from an engineering application perspective. This model is described by state-space equations and is composed of the Francis hydro-turbine model, the fractional-order complex penstocks model, the third-order generator model, and the hydraulic speed governing system model. Based on stability theory for a fractional-order nonlinear system, this study discovers a basic law of the bifurcation points of the above system with a change in the fractional-order α. Secondly, the stable region of the governing system is investigated in detail, and nonlinear dynamical behaviors of the system are identified and studied exhaustively via bifurcation diagrams, time waveforms, phase orbits, Poincare maps, power spectrums and spectrograms. Results of these numerical experiments provide a theoretical reference for further studies of the stability of hydropower stations.

Spent pickling liquors pose a serious environmental problem in most industrialized countries, mainly owing to their corrosive properties and their ferrous iron and hydrochloric acid content. In this paper, spent pickling liquor was used as an inexpensive raw material to prepare Fe₃O₄ magnetic powder via an oxidation method. Being able to recover the dissolved iron from spent pickling liquors would not only salvage a valuable material but also render the effluent environmentally benign. The structure of the Fe₃O₄ magnetic powder was characterized by X-ray diffraction. The morphology and size were characterized by scanning electron microscopy and transmission electron microscopy. Their magnetic properties were tested at room temperature by a vibrating sample magnetometer. In addition, the saturation magnetization of Fe₃O₄ products can be further enhanced to 96.1 emu/g after purification.

Chiral microstructures exist widely in natural biological materials such as wood, bone, and climbing tendrils. The helical shape of such microstructures plays an important role in stress transfer between fiber and matrix, and in the mechanical properties of biological materials. In this paper, helical fiber fragmentation behavior is studied numerically using the finite-element method (FEM), and then, the effects of helical shape on fiber deformation and fracture, and the corresponding mechanical mechanisms are investigated. The results demonstrate that, to a large degree, the initial microfibril angle (MFA) determines the elastic deformation and fracture behavior of fibers. For fibers with a large MFA, the interfacial area usually has large values, inducing a relatively low fragment density during fiber fragmentation. This work may be helpful in understanding the relationship between microstructure and mechanical property in biological materials, and in the design and fabrication of bio-inspired advanced functional materials.

Wind–solar hybrid systems are employed extensively due to certain advantages. However, two problems exist in their application: the PV modules operate at high temperatures, particularly during summer, and low wind power cannot be utilized. To solve these two problems, a novel hybrid system is designed based on PV/thermal systems, in which PV modules are cooled with fans driven by a wind turbine. This paper studies the practicability of the novel hybrid system. First, the electrical performance of the wind turbine is compared using a fan and battery load, respectively. Second, different types and numbers of fans are tested to obtain the largest air volume. Third, the height of the air duct on the back of the PV module is optimized and the cooling effect is studied. Results show that a 24 V DC fan is more appropriate for the novel system than a 12 V DC fan, as it provides a greater air volume, and with a switch wind speed of 3.0 m/s the power of PV module shows a maximum increase of 8.0%.

In this paper, we present an investigation on the tracking performances of feedback control as a function of reference signals. We use multi-objective optimal designs of feedback controls as a fair basis for comparing different control designs, and examine step, ramp, and periodic signals at various frequencies. Through comparing the tracking performances of controls designed with different reference signals, we find that the controls designed with ramp signals perform better in tracking step and ramp references than those designed with step signals. To track periodic signals, we find that the controls designed with periodic signals at the same frequency generally provide the best performance, and those designed with step and ramp signals perform comparably.

For local radiotherapy, a three-dimensional (3D) conformal localized dose planning protocol has been established in this paper to develop a precise and reasonable dose plan. A precalculated 3D dose map for a single source is obtained using the Monte Carlo method, and the spatial dose maps are combined linearly to acquire the dose distribution. The dose distribution is visualized through the real-time display of the isodose line and isodose surface combined with the reconstructed 3D organ groups. By observing 3D dose coverage to the target volume and surrounding tissues, dose planning could be initiated with greater accuracy and precision to avoid dose dead zones and excessively high-dose levels, thus achieving the 3D conformal dose planning objective. Further research into the impact that blockages have on a needle trajectory can be conducted to optimize the insertion accuracy. A treatment planning system was developed to formulate and implement the 3D local treatment plan before the surgery, during the surgery, and after the surgery. Several experiments pertaining to both single-seed and multiple-seed dose distributions were conducted to verify the accuracy of the single-seed dose calculation module and 3D superposition dose calculation in the treatment planning system.

This paper puts forward a new method to achieve flux cored wire TIG welding and uses high-speed photography to analyze the droplet transfer behavior and forces acting on the droplet. The droplet transfer forms include bridging transfer, slag column guided transfer, and non-contact transfer; each of these forms may be observed as the melting position of the welding wire changes. The important role of surface tension in the process of droplet transfer is proposed using static force balance theory and pinch instability theory. The phenomenon of droplet backward swing during welding process could be attributed to the vapor recoil force produced by vapors from the droplet. The welding experiments show that the proposed welding process is stable and that the weld quality produced is good.

To investigate cutting performance in the helical milling of carbon fiber reinforced polymer (CFRP), experiments were conducted with unidirectional laminates. The results show that the influence of cutting parameters is very significant in the helical milling process. The axial force increases with the increase of cutting speed, which is below 95 m/min; otherwise, the axial force decreases with the increase of cutting speed. The resultant force always increases when cutting speed increases; with the increase of tangential and axial feed rates, cutting forces increase gradually. In addition, damage rings can appear in certain regions of the entry edges; therefore, the relationship between machining performance (cutting forces and hole-making quality) and cutting parameters is established using the nonlinear fitting methodology. Thus, three cutting parameters in the helical milling of CFRP, under the steady state, are optimized based on the multi-objective genetic algorithm, including material removal rate and machining performance. Finally, experiments were carried out to prove the validity of optimized cutting parameters.