A series of novel copolymers were successfully synthesized by ring-opening polymerization (ROP) of 3(S)-methyl-morpholine-2,5-dione (MMD) and 5-methyl-5-benzyloxycarbonyl-1,3-dioxan-2-one (MBC) using stannous octoate as catalyst. The copolymers were characterized by means of 1H-NMR and FT-IR spectroscopy. Gel permeation chromatography (GPC) test shows that the average-number relative molecular mass and average-weight relative molecular mass slightly increase with the increase of MBC content in feed. The results of differential scanning calorimetry (DSC) demonstrate that the glass transition temperature of copolymers increases with the increase of MBC content in copolymers. The copolymers of MMD and MBC are amorphous copolymers, as indicated by DSC results, while the homopolymer of MMD is semicrystalline.

Multiple-effect membrane distillation (MEMD) process for enriching semi-volatile organic acids from their individual aqueous solutions was performed by using a hollow fiber-based air gap membrane distillation (AGMD)module with the function of internal heat recovery. Aqueous solutions of glyoxylic acid, glycolic acid, lactic acid, pyruvic acid, malonic acid and glutaric acid were used as model feed. For a feed of 1% (mass fraction), each acid could be enriched for 8–20 times, which depended on the surface tension of the concentrate. The operation performance of MEMD process was characterized by permeation flux J, performance ratio PR and acid rejection rate R. The effects of cold feed-in temperature, heated feed-in temperature, feed-in volumetric flow rate and feed-in concentration on MEMD performance were experimentally evaluated. Maximum values of J, PR and R were 4.8 L/(h·m²), 9.84 and 99.93%, respectively. Moreover, MEMD process demonstrated a fairly good stability in a long-term experiment lasting for 30 d when aqueous solution of 4% (mass fraction) lactic acid was used as a feed.

A refrigerant mixture TJR02 was developed and the comparison experiment was performed on a singlestage vapor compression refrigeration system originally designed for R22. Experimental results show that TJR02 can be directly used in the system without modifying the original system or changing lubricant. By replacing R22 with TJR02, cooling rate gets faster and at least 20% of energy is saved. The actual detection in the standard test-bed verifies the experimental results and indicates that the adoption of TJR02 leads to greater efficiency and wider application. And the lower the refrigeratory temperature is, the more obvious the energy saving effects will be.

A system for mobile robot localization and navigation was presented. With the proposed system, the robot can be located and navigated by a single landmark in a single image. And the navigation mode may be following-track, teaching and playback, or programming. The basic idea is that the system computes the differences between the expected and the recognized position at each time and then controls the robot in a direction to reduce those differences. To minimize the robot sensor equipment, only one omnidirectional camera was used. Experiments in disturbing environments show that the presented algorithm is robust and easy to implement, without camera rectification. The root-mean-square error (RMSE) of localization is 1.4 cm, and the navigation error in teaching and playback is within 10 cm.

To investigate the robust fault detection (RFD) observer design for linear uncertain systems, the H _{t_} index and H _∞ norm are used to describe this observer design as optimization problems. Conditions for the existence of such a fault detection observer are given in terms of matrix inequalities. The solution is obtained by new iterative linear matrix inequality (ILMI) algorithms. The RFD observer design over finite frequency range in which D _f does not have full column rank for a system is also considered. Numerical example demonstrates that the designed fault detection observer has high sensitivity to the fault and strong robustness to the unknown input.

This paper introduces the complexity and particularity of tube-sphere intersection weld (J-groove weld) and establishes the mathematical model of tube-sphere intersection trajectory. Based on the characteristics of J-groove welds, the computational process of welding gun orientation is first simplified. Then the kinematic algorithm of a welding robot is obtained according to screw theory and exponential product formula. Finally, Solidworks and Sim-Mechanics are employed to simulate the kinematics of the welding robot, which proves the feasibility of the kinematic algorithm.

The indirect boundary element method (IBEM) was established to solve the problem of 3-D seismic responses of 2-D topographies, by calculating the free-field responses with the direct-stiffness method and simulating the scattering wave fields with the dynamic Green’s functions of moving distributed loads. The proposed method yields accurate results, because the 3-D dynamic stiffness matrixes used are exact and the fictitious moving distributed loads can be acted directly on the interface between the alluvial valley and the layered half-space without singularity. The comparison with the published methods verifies the validity of the proposed method. And the numerical analyses are performed to give some beneficial conclusions. The study shows that 3-D scattering by an alluvial valley is essentially different from the 2-D case, and that the presence of soil layer affects not only the amplitude value of surface displacements but also the distribution of surface displacements.

In order to give the reasonable width of seismic gaps to prevent the structural pounding during ground motions, the maximum relative displacement of adjacent structures is studied in this paper. The factors that may have effects on the maximum relative displacement are discussed. As for multi-degree-of-freedom (MDOF) systems, they can be equivalent to single-degree-of-freedom (SDOF) systems with the influences of high modes neglected. The results show that the period ratio, height ratio and peak ground acceleration are the main factors that have great effects on the maximum relative displacement of adjacent structures. The maximum relative displacement of MDOF systems can be obtained from calculating the maximum relative displacement of the equivalent SDOF systems.

Corn steep liquor (CSL) is an important raw material that has high nutritional value and serves as a nitrogen source. Biotin in CSL is especially of great importance to fermentation. In order to develop a fast, versatile, cheap, and environmentally safe analytical method for quantifying vitamins B2 (VB2), B3 (VB3), B6 (VB6) and B7 (VB7) in CSL, the near-infrared spectroscopy (NIR) measurements of 66 samples (22 batches) of CSL were analyzed by partial least-square regression (PLSR). Multivariate models developed in the NIR regions showed good predictive abilities for VB2, VB3, VB6 and VB7. Results confirmed the probability of the multivariate spectroscopic approach as a replacement for expensive and time-consuming conventional chemical methods.

High-temperature coal tar was extracted with petroleum ether (PE) under ultrasonic irradiation and the extracts were analyzed with gas chromatograph/mass spectrometer. The acearylene fractions including acenaphthylene, aceanthrylene and cyclopentapyrene were enriched together and named E, which was then transferred to a cartridge in Isolera-One flash chromatography. Three groups of compounds were eluted out with ethyl acetate/PE mixed solvent (volume ratio 1:9) and named E₁, E₂ and E₃ according to their main components. Acenaphthylene accounted for 78.2% in E1, aceanthrylene 71.6% in E₂ and cyclopentapyrene 75.9% in E₃, respectively. The three groups of acearylenes were purified by Sephadex LH-20 column chromatography with ethanol/cyclohexane mixed solvent (volume ratio 1:4), and then confirmed with nuclear magnetic resonance spectrometer. This method indicates that flash chromatography has a good effect on separating the compounds with a similar structure after extraction under ultrasonic irradiation.

The local characteristics of multi-dimensional random variables are seldom considered in the general modeling method of multivariate copula. A new modeling method, called pair-copula construction, is introduced to remedy this defect. Different types of copula distribution functions are allowed to be introduced in this method. Correspondingly, the related characteristics of complex multivariate can be described by a cascade of pair-copula acting on two variables at a time. In the analysis of asynchronism-synchronism of regional precipitation in WED interbasin water transfer areas, the pair-copula construction method is compared with the general modeling method of multivariate copula. The results show that the local dependence structure would exist among hydrologic variables even in three-dimensional cases. In this situation, the general modeling method of multivariate copula would face difficulties in fitting distribution. However, the pair-copula construction method could capture the local information of hydrologic variables efficiently by introducing different types of copula distribution functions. Moreover, the compensation capacity of water resources is strong in different hydrological areas of WED water transfer project. The asynchronous frequency of wetness and dryness is 69.64% and the favorable frequency for water transfer is 46.15%.