With the rapid growth in demand for industrial gas in steel and chemical industries, there has been significant emphasis placed on the development of China’s large-scale air separation technology. Currently, the maximum capacity of a single unit has been able to attain 120 000 Nm³/h (oxygen), and the specific power consumption of 0.38 kWh/m³. This paper reviews the current state-of-the-art for large-scale cryogenic air separation systems being deployed in China. A brief introduction to the history and establishment of the large-scale cryogenic air separation industry is presented. Taking the present mainstream large-scale air separation unit operating at 60 000 Nm³/h (oxygen) as an example, the technological parameters and features of the involved key equipment, including a molecular sieve adsorber, air compressor unit, plate-fin heat exchanger, turbo-expander and distillation column are described in detail. The developing 80 000–120 000 Nm³/h air separation processes and equipment are also introduced. A summary of the existing problems and future developments of these systems in China are discussed.

Accurate thermal expansion data of material at low temperatures are important in material selection and structural design for a cryogenic system. In this study, an experimental setup with a proportional-integral-derivative (PID) temperature control system was developed to measure the thermal expansion of solid materials at low temperatures (77–293 K), using the strain gage method. To avoid the impact of the varied sensitivity coefficient of the strain gage with the temperature to ensure an accurate measurement, we corrected the sensitivity coefficient in the temperature range of 77–293 K, by comparing the measured thermal expansion data for 304 stainless steel with the source data from the National Institute of Standards and Technology, USA. With the corrected sensitivity coefficient of the strain gage, the measured linear contractions of oxygen-free copper become quite consistent with the NIST data (with a relative deviation of 2.37%) for the cooling-down process from 293 K to 80 K.

The wrinkling phenomenon is a commonly-known problem in many fields of engineering applications. Using a general structural analysis framework of the vector-form hybrid particle-element method (VHPEM), this paper presents a newly developed shell-based numerical model for the geometrically nonlinear wrinkling analysis of thin membranes. VHPEM is rooted in vector mechanics and physical perspective. It discretizes the analyzed domain into a group of finite particles linked by canonical elements, and the motions of the free particles are governed by Newton’s second law while the constrained ones follow the prescribed paths. An adaptive convected material frame is adopted for a general kinematical description. Internal forces related to the non-zero bending rigidity of a membrane can be efficiently evaluated by the rotation deformation in a set of deformation coordinates after eliminating rigid body motions simply by a fictitious reverse motion. To overcome the numerical difficulties associated with wrinkles, a pseudo-dynamic scheme using the explicit time integration is introduced into this method. Structural nonlinearity can be easily handled without iterative operations or any other special modification. The wrinkling behavior can be readily obtained by performing a pseudo bifurcation analysis incorporated into the VHPEM. The numerical results reveal that the VHPEM has good reliability and accuracy on solving the membrane wrinkling problem.

With the rapid development of bridge engineering in China, multi-span cable-stayed bridges have become one of the main structures of modern highways and railways for crossing rivers or straits. In this study, a 1:100 scale model of a three-tower cable-stayed bridge was tested using a shaking table array system. The mechanism associated with the seismic response of the scale model under uniform and non-uniform excitations was clarified. The results from the tests indicated that: (1) the strong vibration responses of the main girder and towers under four different horizontal earthquake wave excitations were identified, and the seismic responses of the scale model were most evident under uniform Jiangxin (JX) wave excitation; (2) the seismic performances of the main girder and towers of the scale model were adversely affected by traveling wave effects, especially when the wave velocity exceeded 616 m/s, which suggests that traveling wave effects should be considered in the seismic design of multi-tower cable-stayed bridges; (3) when the peak acceleration value of the El Centro (EC) wave reached 4.0 m/s², shear failure of the bearing of the middle tower first appeared. This kind of shaking table tests will help to improve our understanding of dynamic performance, and will be especially useful in the design process and numerical simulation of multi-span cable-stayed bridges with large span subjected to spatially varying earthquake ground motions.

This paper presents a new triaxial apparatus for testing soil water retention curves (SWRCs) under different temperatures. The components of this modified apparatus, as well as the special features of each component, were described. The key part of this innovative apparatus was the temperature control system, which was cooperated with a loading system and a suction control system. Different methods of heating were compared and a more effective method, which used a heating element around the pressure chamber, was consequently adopted. Under different temperatures (25, 40, and 60 °C) and different net mean stresses (40, 100, and 200 kPa), typical results from the SWRCs tests for unsaturated silty clay were presented and analyzed. The experimental results show that the volumetric water content reduces with the increasing temperature at constant suction.

In this research, the process analytical technology (PAT) framework is used to optimize the performance of the wastewater treatment process in poultry industry. Two responses, turbidity and sludge volume index (SVI), are of main manufacturer’s interest. Initially, the moving average (MA) and moving range (MR) control charts are established for each response. The 3³ full factorial design with two replicates is then used for conducting experimental work. The weighted additive model in fuzzy goal programming is formulated, and then employed to determine the combination of optimal factor settings. Finally, confirmation experiments follow at the combination of optimal factor settings. The results show that the actual process index for turbidity is improved from 1.34 to 5.5, while it is enhanced from 1.46 to 1.93 for SVI. Moreover, the multiple process capability index is improved significantly from 1.95 to 10.6, which also indicates that the treatment process becomes highly capable with both responses concurrently. Further, the process standard deviations at initial (optimal) factor settings are 2.16 (1.27) and 6.02 (3.39) for turbidity and SVI, respectively. These values show significant variability reductions in turbidity and SVI by 41.22% and 77.75%, respectively. Such improvements will lead to huge savings in quality and productivity costs. In conclusion, the PAT framework is found to be an effective approach for optimizing the performance of the wastewater treatment process with multiple responses.