Rate adaptation for dynamic adaptive streaming over HTTP in content distribution network

Recently the 3rd Generation Partnership Project (3GPP) and the Moving Picture Experts Group (MPEG) specified Dynamic Adaptive Streaming over HTTP (DASH) to cope with the shortages in progressive HTTP based downloading and Real-time Transport Protocol (RTP) over the User Datagram Protocol (UDP), shortly RTP/UDP, based streaming. This paper investigates rate adaptation for the serial segment fetching method and the parallel segment fetching method in Content Distribution Network (CDN). The serial segment fetching method requests and receives segments sequentially whereas the parallel segment fetching method requests media segments in parallel. First, a novel rate adaptation metric is presented in this paper, which is the ratio of the expected segment fetch time (ESFT) and the measured segment fetch time to detect network congestion and spare network capacity quickly. ESFT represents the optimum segment fetch time determined by the media segment duration multiplied by the number of parallel HTTP threads to deliver media segments and the remaining duration to fetch the next segment to keep a certain amount of media time in the client buffer. Second, two novel rate adaptation algorithms are proposed for the serial and the parallel segment fetching methods, respectively, based on the proposed rate adaptation metric. The proposed rate adaptation algorithms use a step-wise switch-up and a multi-step switch-down strategy upon detecting the spare networks capacity and congestion with the proposed rate adaptation metric. To provide a good convergence in the representation level for DASH in CDN, a sliding window is used to measure the latest multiple rate adaptation metrics to determine switch-up. To decide switch-down, a rate adaptation metric is used. Each rate adaptation metric represents a reception of a segment/portion of a segment, which can be fetched from the different edge servers in CDN, hence it can be used to estimate the corresponding edge server bandwidth. To avoid buffer overflow due to a slight mismatch in the optimum representation level and bandwidth, an idling method is used to idle a given duration before sending the next segment. In order to solve the fairness between different clients who compete for bandwidth, the prioritized optimum segment fetch time is assigned to the newly joined clients. The proposed rate adaptation method does not require any transport layer information, which is not available at the application layer without cross layer communication. Simulation results show that the proposed rate adaptation algorithms for the serial and the parallel segment fetching methods quickly adapt the media bitrate to match the end-to-end network capacity, provide an advanced convergence and fairness between different clients and also effectively control buffer underflow and overflow for DASH in CDN. The reported simulation results demonstrate that the parallel rate adaptation outperforms the serial DASH rate adaptation algorithm with respect to achievable media bitrates while the serial rate adaptation is superior to the parallel DASH with respect to the convergence and buffer underflow frequency.     

Characterisation of trypsin purified from the viscera of Tunisian barbel (Barbus callensis) and its application for recovery of carotenoproteins from shrimp wastes

Trypsin was purified from the viscera of barbel by precipitation using ammonium sulphate (0-80%), Sephadex G-100, and Mono Q-Sepharose ion exchange chromatography. The trypsin was purified 27-fold, with 79 U/mg specific activity and 31% recovery. The enzyme had a molecular weight of 24 kDa; purified trypsin appeared as a single band on native-PAGE. The optimum pH and temperature for enzyme activity were pH 10.0 and 55 °C with BAPNA used as a substrate. The N-terminal amino acid sequence of the first 12 amino acids of the purified trypsin was IVGGYECTPYSQ. The Michaelis-Menten constant (K_m) and catalytic constant (k_cat) values of the enzyme were 0.018 mM and 1.21 s⁻¹, respectively. The study also investigated the effects of purified trypsin on the recovery of carotenoproteins from shrimp (Parapenaeus longirostris) shells through hydrolysis using 1.0 U barbel trypsin/g shrimp shells for 1 h at 30 °C. The freeze-dried carotenoproteins recovered contained 71.09% protein, 16.47% lipid, 7.78% ash, and 1.79% chitin.     

Some Theorems in the Isotropic Theory of Microstretch Thermoelasticity with Microtemperatures

This article is concerned with the linear theory of microstretch thermoelastic bodies with microtemperatures. It is shown that there is exists the coupling of microtation vector field with the microtemperatures for isotropic bodies. The existence of a generalized solutions is proved by means of the semigroup of linear operators theory and the asymptotic behavior of the solutions is studied.     

A novel integer programming formulation with logic cuts for the U-shaped assembly line balancing problem

U-shaped assembly lines are regarded as an efficient configuration in Just-In-Time manufacturing. Balancing the workload in these lines is an unsolved problem that attracted significant research within the past two decades. We present a novel integer programming formulation for U-shaped line balancing problems, where cycle time, the interval between two consecutive outputs, is known and the aim is to minimize the number of workstations. To enhance the efficiency of the LP relaxation of the new formulation, we present three types of logic cuts (assignable-station-cuts, task-assignment-cuts and knapsack-cuts) that exploit the inherent logic of the problem structure. The new formulation and logic cuts are tested on an extensive set of benchmark problems to provide a comparative analysis with the existing models in the literature. The results show that our novel formulation augmented by assignable-station-cuts is significantly better than the previous formulations.     

Angiotensin I‐converting enzyme inhibitory peptides FQPSF and LKYPI identified in Bacillus subtilis A26 hydrolysate of thornback ray muscle

Angiotensin I‐converting enzyme (ACE) inhibitory peptides have been searched in thornback ray (Raja clavata) muscle hydrolysed with Bacillus subtilis A26 proteases until a hydrolysis degree of 18.35%. The hydrolysate showed an IC₅₀ of 0.83 mg mL^?1. To identify peptides responsible for this activity, the extract was eluted through size‐exclusion chromatography and fractions collected. The highest ACE inhibitory activity was found for fractions F2 and F3 which had IC₅₀ of 0.42 and 0.51 mg mL^?1, respectively. These fractions were analysed by nano‐liquid chromatography coupled to tandem mass spectrometry (nLC‐MS/MS). A total of 131 and 108 peptide sequences mainly derived from actin, myosin heavy chain and procollagen alpha 1 chain proteins were identified in fractions F2 and F3, respectively. FQPSF and LKYPI showed the best results with an IC₅₀ of 12.56 and 27.07 μM, respectively. These results prove the potential of thornback ray muscle hydrolysate as a source of ACE inhibitory peptides.     

Development of an optimal daylighting controller

A new lighting and daylighting control strategy is modeled and evaluated against conventional lighting and daylighting controls. The new lighting and daylighting control strategy can be incorporated in an energy management and control system (EMCS) to operate and control lighting fixtures in any indoor space. The new daylighting control can also be modeled and integrated in detailed building energy simulation tools. Through a validation analysis, it was found that the new control strategy provides more energy savings than conventional daylighting controls. Moreover, the validation analysis has indicated that existing daylighting control simulation analysis tools could overestimate lighting energy savings associated with daylighting controls. Moreover, it was also found that if calculated solar and illuminance data are used instead of measured solar radiation data, the errors in predicting lighting energy use when daylighting controls are utilized can be significant.     

Solvent and Emulsion Extractions of Gallic Acid by Tributylphosphate: Mechanisms and Parametric Study

The aim of this paper was to study solvent extraction or liquid-liquid extraction (LLE) and extraction by emulsion (ELM) of gallic acid, a biomolecule present in many plants. A mechanism involving three tributylphosphate molecules for one molecule of undissociated gallic acid with co-extraction of water was found in LLE. ELM process is as fast as LLE and more efficient; in addition, it is more environmentally-friendly because lower extractant concentrations and smaller organic phase volumes were needed.     

Influence of degree of hydrolysis on functional properties and angiotensin I‐converting enzyme‐inhibitory activity of protein hydrolysates from cuttlefish (Sepia officinalis) by‐products

BACKGROUND: In Tunisia the cuttlefish‐processing industry generates large amounts of solid wastes. These wastes, which may represent 35% of the original material and constitute an important source of proteins, are discarded without any attempt at recovery. This paper describes some functional properties and the angiotensin I‐converting enzyme (ACE)‐inhibitory activity of protein hydrolysates prepared by hydrolysis of cuttlefish (Sepia officinalis) by‐products with crude enzyme extract from Bacillus licheniformis NH1. RESULTS: Cuttlefish by‐product protein hydrolysates (CPHs) with different degrees of hydrolysis (DH 5, 10 and 13.5%) were prepared. All CPHs contained 750–790 g kg^?1 proteins. Solubility, emulsifying capacity and water‐holding capacity increased while fat absorption and foaming capacity decreased with increasing DH. All hydrolysates showed greater fat absorption than the water‐soluble fraction from undigested cuttlefish by‐product proteins and casein. CPHs were also analysed for their ACE‐inhibitory activity. CPH3 (DH 13.5%) displayed the highest ACE inhibition (79%), with an IC₅₀ value of 1 mg mL^?1. CONCLUSION: Hydrolysis of cuttlefish by‐product proteins with alkaline proteases from B. licheniformis resulted in a product with excellent solubility over a wide pH range and high ACE‐inhibitory activity. This study suggests that CPHs could be utilised to develop functional foods for prevention of hypertension. Copyright © 2010 Society of Chemical Industry