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Owing to the unique advantages in flight altitude, dwelling time and wide coverage area, stratospheric airships provide permanent monitoring and surveillance for both civil and military applications. Here we propose a semi-rigid stratosphere airship design with circumferential high-pressure inflatable rings and a longitudinal carbon fiber skeleton supported inside. We perform numerical simulations to analyze the deformation characteristics during the whole ascending and descending process. An equivalent internal gradient pressure model of helium is established based on the capsule shape and buoyancy-weight equilibrium conditions. The implicit dynamic method is used to deal with the large deformation of the airship capsule under a low negative pressure condition. Deformation and load-bearing performance of the airship capsule, inflatable ring, skeleton, and suspension line are obtained under different working conditions. The results show that the airship, supported with the inflatable rings and the suspension lines, effectively maintains the shape and ensures the stiffness during the ascending, dwelling, and descending stages, especially suffering from negative pressure.

This article studies two main ways of gamut expansion: improving the color purity of the primary color and increasing the number of primary colors. A program for the gamut coverage of the multi- primary color display system is written. The color coordinates of the laser TV developed by ourselves are measured and the actual value of color gamut is calculated. The test data verifies the simulation result.

Self-developed three- primary color laser projection TV based on RGB (RED, GREEN, BLUE） laser diode is given by this paper. Laser diode has very narrow line-width, high color purity and saturation, and displays more colorful and gorgeous image. In this work, the Helmholtz-Kohlrausch effect is applied for studying the enhanced perceived brightness of the RGB laser projection television. The experiments are designed for the difference perceived brightness between the RGB laser projector TV and the Blue laser- excited phosphor laser projection TV. The ratio of the enhanced perceived brightness of RGB laser projector TV is evaluated.

We present a method to produce a hollow laser beam with adjustable profile distribution using a tapered optical fiber. The dependence of the dark spot size (DSS), hollow beam width (HBW), and transverse field intensity distribution of the hollow beam on the incidence angle of the laser beam, cone angle of the tapered fiber, and working distance are analyzed theoretically and experimentally. The study shows that a high-power hollow laser beam with excellent propagation properties can be achieved by using a tapered fiber with certain parameters. The proposed technique is simple, flexible, and easy to control and operate.

Phase modulation is a crucial step when the frequency-based wavefront optimization technique is exploited to measure the optical transmission matrix (TM) of a scattering medium. We report a simple but powerful method, direct digital frequency synthesis (DDS) technology to modulate the phase front of the laser and measure the TM. By judiciously modulating the phase front of a He–Ne laser beam, we experimentally generate a high quality focus at any targeted location through a 2 mm thick 120 grit ground glass diffuser, which is commercially used in laser display and laser holographic display for improving brightness uniformity and reducing speckle. The signal to noise ratio (SNR) of the clear round focus is ∼ 50 and the size is about 44 μm. Our study will open up new avenues for enhancing light energy delivery to the optical engine in laser TV to lower the power consumption, phase compensation to reduce the speckle noise, and controlling the lasing threshold in random lasers.

Partial nitrification granular sludge (PNGS) treating domestic sewage was successfully cultivated in a sequencing batch reactor through shortening settling time gradually based on total suspended solids in the effluent. The granulation process contained the washout of a part of flocculent sludge, the gathering of the remaining flocculent sludge, and the growth of granules. Depending on the measurement of extracellular polymer substance (EPS), including polysaccharide (PS) and protein during different periods, it was concluded that EPS was the key factor for PNGS formation and PS was the main component of EPS in the PNGS biomass. PS was mainly from the secretion of heterotrophic bacteria during endogenous respiration period. The treatment ability of PNGS was improved effectively by high ammonia concentration in a short time (18 d), and then, PNGS achieved an efficient and stable partial nitrification for domestic sewage at 20°C. The ammonia removal rate reached 0.7 kg N m−3 d−1, and the nitrite acc...

Cooperative driving with V2V communication is under extensive investigation, because of its potential to increase the safety, reliability, connectivity, and autonomy of transportation systems. This paper studies the problem of connected cruise control (CCC) for a platoon of human-driven and autonomous vehicles. Motional data, such as distance and velocity information, are transmitted by vehicle-to-vehicle (V2V) communication between connected vehicles. Taking into account the communication latency and unpredictable behavior in the leading vehicle, we formulate the CCC problem as an adaptive optimal control problem with input delay and disturbance. A novel data-driven control solution is proposed for the vehicle platoon, which guarantees that each vehicle can achieve safe distance and desired common velocity. Incorporating adaptive dynamic programming technique with sampled-data system theory, a data-driven adaptive optimal controller is learned from sampled data, without the knowledge of the human or vehicle dynamics of the platooning vehicles. Stability and robustness analyses are provided by means of input-to-state stability theory. Numerical results confirm the efficacy of our method.

A matrix analysis for free-space switching networks, such as perfect shuffle-exchange omega, crossover and Banyan is presented. On the basis of matrix analysis, the equivalence of these three switching networks and the route selection between input and output ports are simply explained. Furthermore,an optical crossover switching network, where MQW SEED arrays are used as electrically addressed four-function interchange nodes, is described and the optical crossover interconnection of 64 x 64, and high-speed four-function, interchange nodes is demonstrated in the experiment.