Automatic Landing Assist System Using IMU+P<Emphasis Type="Italic">n</Emphasis>P for Robust Positioning of Fixed-Wing UAVs

This research proposes using a robust Perspective-n-Point (PnP) solution for an automatic landing assistant system for landing a fixed-wing, unmanned, aerial vehicle (UAV) on a runway. Specifically, we attack the problems of: 1) the difficulty in localizing markers on the ground; and 2) multiple candidate poses from PnP algorithms. The former issue can be resolved based on a least-square-based calibration between the camera and the inertial moment unit (IMU) plus geometrical information with consideration given to Lie’s algebra: SO(3). The latter issue has been presented during a long history in the pose estimation field. For an aerial vehicle that can freely move, we propose to resolve this problem using a fusion algorithm between the IMU and PnP, based on object space collinearity. We experiment and analyze that this fusion solution is among the best methods to enhance runway positioning accuracy. Furthermore, discussion based on availability of equipment is presented.     

Maillard reaction in natural rubber latex: Improvement of concentration process

Maillard reaction in natural rubber (NR) latex was studied by treating fresh latex with formaldehyde and glutaraldehyde. Volatile fatty acid number of the treated latex could be lower than acceptable limit (< 0.08) for more than 20 days. Attenuated total reflectance infrared spectroscopy and sodium dodecyl sulfate polyacrylamide gel electrophoresis revealed the occurrence of protein crosslinks in the treated latex. NR treated with glutaraldehyde has much higher nitrogen content than NR treated with formaldehyde and untreated NR, respectively. Colloidal stability of rubber particles, represented by pH, zeta potential, viscosity, and particle size distribution information, were unchanged after treating the latex with formaldehyde. Treatment of the fresh latex with glutaraldehyde 100 and 200 mmol/kg of latex led to the aggregation of rubber particles. Interestingly, the Maillard crosslinking of proteins in fresh latex could efficiently promote the transfer of rubber particles from the serum phase into the cream phase during centrifugation. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45224.     

Study of chitosan and its derivatives as preservatives for field natural rubber latex

In this study, the chitosan and its derivatives were tested for their preservative activities for field natural rubber (NR) latex. A series of chitosans with different molecular weights were obtained by nitrous acid depolymerization. The chemically modified chitosans, N‐carboxymethyl chitosan (NCMCh), N‐sulfated chitosan (NSCh), and N‐(2‐hydroxy)propyl‐3‐trimethylammonium chitosan chloride (NHTACh), were prepared from high and low‐molecular weight chitosans. Preservative activities for field NR latex of these chitosans were investigated based on the measurement of volatile fatty acids (VFA) number of the treated latex. The preservative activities of chitosan increased with decreasing molecular weights. The low‐ molecular weight NSCh and NHTACh exhibited good preservative activity for the latex. By the use of low‐molecular weight NHTACh in combination with octylphenol poly (ethyleneglycolether) (Nonidet P40), the latex was successfully preserved for more than 1 month in the low‐ammonia condition. The results showed an attractive feature to develop the preservative system, which was possible to reduce the concentrations of ammonia and carcinogenic nitrosamine in the NR latex. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Creaming of skim natural rubber latex with chitosan derivatives

To recover residual rubber from skim natural rubber (SNR) latex, a novel method was developed on the basis of the use of water‐soluble chitosan derivatives. An anionic chitosan derivative, N,O‐carboxymethyl chitosan (CMCh), and a cationic chitosan derivative, N‐(2‐hydroxy)propyl‐3‐trimethylammonium chitosan chloride (HTACh), were prepared. It was found that the creaming process could be achieved with both chitosan derivatives. By the addition of 7.34–10.3‐g/L CMCh, SNR latex was almost completely creamed, and no coagulation of SNR particles in the cream phase occurred. In the case of HTACh, the creaming process was achieved with a lower concentration (<3.70 g/L) than in the case of CMCh, but the size of SNR particles in the cream phase was larger. Solid‐state ¹³C‐NMR, thermogravimetric analysis, and ζ potential measurement results provided evidence that the creaming of SNR latex with CMCh and HTACh was controlled by the depletion flocculation and adsorption mechanisms, respectively. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Effects of reaction conditions on poly(methyl methacrylate) polymerized by living radical polymerization with iniferter

Living radical polymerization of methyl methacrylate (MMA) through the use of benzyl diethyl dithiocarbamate (BDC) was studied. The aim was to investigate the role of the concentration, BDC‐to‐MMA mol ratio, and reaction time upon the molecular weight, polydispersity, and conversion of the product. It was found that the molecular weight and the conversion increase with increase of the concentration at the expense of low polydispersity. The reaction time also played a significant role, especially at a relatively long reaction time where molecular weight, polydispersity, and conversion increased with increasing reaction time. In terms of the mol ratio effect, it was found that there was a critical mol ratio for maximum conversion. The results indicate that the kinetics of polymerization of MMA through the use of a BDC inifeter is different from that in the presence of a conventional initiator. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 938–944, 2000     

Synthesis of polyisoprene-poly(methyl methacrylate) block copolymers by using polyisoprene as a macro-iniferter

Summary Polyisoprene (PI) was pre-polymerized by using benzyl diethyldithiocarbamate (BDC) as an iniferter. The obtained PI was subsequently used to react with methyl methacrylate (MMA) in order to investigate whether the relevant block copolymers can be achieved. Results from ¹H-NMR and GPC reveal that the PI-PMMA block copolymers were formed. This suggests that polymerization of isoprene through the use of BDC proceeded via a (psuedo) “living” mechanism. Received: 9 August 1999/Revised version: 27 September 1999/Accepted: 1 October 1999