Analysis of 3D PPN guidance laws for nonmaneuvering target
Unlike the traditional ways adopted by most of the researchers, the rotating angle of relative velocity is adopted in this work as the independent variable to analyze the analytical solution of impact angle, capture region (with or without finite line of sight (LOS) turn rate constraint), range to go, time to go, and a defined fuel cost of a traditional pure proportional navigation (PPN) guidance law for both nonmaneuvering moving, and stationary targets.
The three dimensional guidance system design of terminal attack phase for exo-atmospheric kill vehicle
Abstract A novel terminal guidance system with a pulse-width-pulse-frequency (PWPF) modulator based on variable dead zone is designed for exo-atmospheric kill vehicle (EKV). At first, a three dimensional (3D) missile-target engagement kinematics is established on the line-of-sight (LOS) coordinate system, the guidance law is compensated by estimated maneuvering acceleration of target from nonlinear disturbance observer (DO). Secondly, a 3D terminal sliding mode guidance law with gradually increasing robustness is proposed for EKV, and the finite time stability of closed system is strictly proven. A PWPF modulator with variable dead zone is proposed to resist the sensitivity of LOS angle with relative distance decreasing, and the stability of modulator is proven by describing function technique. Finally, the guidance performances are assessed through a numerical simulation, the proposed guidance law is better attack precision than traditional guidance law, and the PWPF modulator with variable dead zone is more reasonable in fuel allocation and smaller on miss distance than traditional PWPF modulator.
Air scrubbing techniques for ammonia and odor reduction at livestock operations : review of on-farm research in the Netherlands
Acid scrubbers and biotrickling filters have been developed for ammonia (NH3) removal at pig and poultry houses 
in The Netherlands over the last 20 years to prevent acidification and eutrophication of soils. Because of growing 
suburbanization, odor removal is increasingly considered important as well. In this review, we report the results of the on-farm 
research on full-scale operated scrubbers for treatment of exhaust air from animal houses with regard to NH3 and odor 
removal in The Netherlands. The NH3 removal of acid scrubbers ranged from 40% to 100% with an overall average of 96%. 
The NH3 removal of biotrickling filters ranged from -8% to +100% with an overall average of 70%. Minimum empty bed air 
residence times (EBRTs) were 0.4 to 1.1 s. For acid scrubbers, process control with pH measurement and automatic water 
discharge is sufficient to guarantee sufficient NH3 removal. For biotrickling filters, however, improvement of process control 
is necessary to guarantee sufficient NH3 removal. The odor removal of acid scrubbers ranged from 3% to 51% with an overall 
average of 27%. The odor removal of biotrickling filters ranged from -29% to +87% with an overall average of 51%. 
Minimum EBRTs were 0.5 to 2.3 s. Further research is necessary to explain this variation and to improve the odor removal 
efficiency of both acid scrubbers and biotrickling filters.