Adaptive admission/congestion control policies for CDMA-based wireless internet

Radio resource management (RRM) is vital for the next generation wireless networks. RRM comprises many functionalities and this paper focuses on the investigation of the performance of several adaptive call admission/ congestion control policies based on a window-measurement estimation of the status of the buffer at the base station under the hybrid TDMA/CDMA access scheme. In our study, we interrelate the physical limitations of the base stations (i.e. the number of transmission and reception modems), call and burst level traffic, instantaneous buffer conditions and end-to-end bit error performance in one queuing problem. Subsequently, a windowmeasurement estimator is implemented to estimate the likelihood of buffer congestion at the base station. Accordingly, the traffic loads shall be controlled. We use event-driven simulation to simulate the multimedia integrated CDMA networks where heterogeneous traffic users are multiplexed into a simple TDMA frames. The simulation results show outstanding performance of the proposed call admission/congestion control policies in guaranteeing QoS requirements

Adaptive admission/congestion control policies for CDMA-based wireless internet

Radio resource management (RRM) is vital for the next generation wireless networks. RRM comprises many functionalities and this paper focuses on the investigation of the performance of several adaptive call admission/ congestion control policies based on a window-measurement estimation of the status of the buffer at the base station under the hybrid TDMA/CDMA access scheme. In our study, we interrelate the physical limitations of the base stations (i.e. the number of transmission and reception modems), call and burst level traffic, instantaneous buffer conditions and end-to-end bit error performance in one queuing problem. Subsequently, a windowmeasurement estimator is implemented to estimate the likelihood of buffer congestion at the base station. Accordingly, the traffic loads shall be controlled. We use event-driven simulation to simulate the multimedia integrated CDMA networks where heterogeneous traffic users are multiplexed into a simple TDMA frames. The simulation results show outstanding performance of the proposed call admission/congestion control policies in guaranteeing QoS requirements

Removing of heavymetals from water by chitosan nanoparticles

Chitosan was prepared by deacetylation of chitin. The prepared chitosan has characterized bymolecular weight, degree of deacetylation, and ash %. Chitosan nanoparticles were prepared byionotropic gelation of chitosan with tripolyphosphate anions. The structure and particle size of chitosan nanoparticles have confirmed via FTIR analysis and TEM imaging.The chitosan nanoparticles were used in water treatment to remove metal ions from sample contains 20 ppm from each Fe+2, Mn+2, Zn+2 and Cu+2.The optimum conditions for this study were at 2 g/l of chitosan nanoparticles, pH 7 and 30 min of mixing time. Chitosan showed the highest performance under these conditions with removing percent 99.94% 80.85% 90.49% and 95.93% from Fe+2, Mn+2, Zn+2 and Cu+2 respectively

Activity and stability of immobilized Candida rugosa lipase on chitosan coated Fe3O4 nanoparticles in aqueous and organic media

Fe3O4 (magnetite) nanoparticles were prepared by coprecipitation method, coated by chitosan and functionalized by glutaraldehyde. Lipase enzyme from Candida rugosa was immobilized on the prepared particles via cross linking reaction. Synthesis steps and characterization were examined by XRD, TEM, and FTIR.  The immobilization conditions were 10 mL of phosphate buffer (0.1 M, pH 6.5) containing 30 mg of  functionalized magnetic chitosan nanoparticles and 2.0 mg·mL-1 of lipase, immobilization temperature of 4 ℃ and immobilization time of 1 h. Under these conditions, lipase was successfully immobilized with loading capacity of 87 mg/g. The immobilized enzyme showed good operational and storage stability, where it remained stable after 30 days of storage at 4â—¦C.and retained about 61% of its initial activity after twenty repeated uses. Finally enzymatic catalyze synthesis of butyl and hexyl oleate at 40 â—¦C with shaking (200 rpm) was realized in n-hexane and confirmed by GC analysis

Removing of heavymetals from water by chitosan nanoparticles

Chitosan was prepared by deacetylation of chitin. The prepared chitosan has characterized bymolecular weight, degree of deacetylation, and ash %. Chitosan nanoparticles were prepared byionotropic gelation of chitosan with tripolyphosphate anions. The structure and particle size of chitosan nanoparticles have confirmed via FTIR analysis and TEM imaging.The chitosan nanoparticles were used in water treatment to remove metal ions from sample contains 20 ppm from each Fe+2, Mn+2, Zn+2 and Cu+2.The optimum conditions for this study were at 2 g/l of chitosan nanoparticles, pH 7 and 30 min of mixing time. Chitosan showed the highest performance under these conditions with removing percent 99.94% 80.85% 90.49% and 95.93% from Fe+2, Mn+2, Zn+2 and Cu+2 respectively

Age at puberty and accelerometer-measured physical activity:findings from two independent UK cohorts

Background It is unclear if puberty timing influences future physical activity (PA). Aim To investigate the association of puberty timing with PA across adolescence and adulthood. Subjects and methods Data were from two British cohorts. Participants from an adolescent birth cohort (females = 2349, males = 1720) prospectively reported age at menarche and voice break and had PA recorded by Actigraph accelerometers at ages 14 years and 16 years. A cohort of middle-aged and older adults (40–70 years; females = 48,282; males = 36,112) recalled their age at puberty and had PA (mean acceleration; mg) measured by AxivityAX3 accelerometers. Results After adjustment for age, education, smoking and BMI, per 1-year older age at menarche was associated with higher mean counts/minute at age 14 years (0.07 SD counts/minute; 95% CI = 0.04–0.11) with associations attenuated at age 16 years (0.02; −0.03–0.07). Differences in mean acceleration per older year at menarche were close to the null in women aged 40–49 years (0.02 mg; 0.01–0.03), 50–59 years (0.01; 0.00–0.02) and 60–70 years (0.01; 0.00–0.01). Age at voice break and PA associations were close to the null in both cohorts. Conclusion We found a positive association between puberty timing and PA in females which weakened at older ages and limited evidence of an association at any age in males