Investigation of muscle fatigue of the archer’s during endurance shooting

Endurance of Drawing-Aim-Release (DAR) during the shooting process in archery will be causing the muscles to fatigue. Besides, the archer's inability to use the right muscles for DAR will lead to a muscle injury as well as dropping the performance. This study aims to monitor the localized muscle fatigue of an archer during the repetitive DAR and its effect to the archer’s performance. Wet electrode sensors were placed on the specific muscles that are heavily involved in DAR such as Muscle Extensor Digitorum (MED) on the archer's bow arm and the Supraspinatus muscle at the shoulder. In order to induce fatigue, the archer has shot 72 arrows continously in 2 rounds of set. The surface electromyography (sEMG) signals of the muscle contraction are recorded during the shooting for the post-processing analysis. Each score of the shooting was also recorded to correlate with the effect of muscle fatigue to the archer’s performance. The finding of this study is that the MED and Supraspinatus begin to fatigue toward the end of each shooting round. The Root Mean Square (RMS) and Median Frequency (MDF) values for both targeted muscles increased significantly during the 6th end compare to the 1st end. It is also found that there is no correlation between muscle fatigue on MED and Supraspinatus to the score obtained by the archer where the F value is lower than F-critical while Draw (1.9339), Aim (1.3754) and Release (0.6515) phases. In conclusion, this experiment benefits archers and coaches to identify which muscles are vigorously used during the DAR process and allows for precaution and prevention procedures

CMOS ring oscillator delay cell performance: a comparative study

A common voltage-controlled oscillator (VCO) architecture used in the phase locked loop (PLL) is the ring oscillator (RO). RO consist of number of inverters cascaded together as the input of the first stage connected to the output of the last stage. It is important to design the RO to be work at desired frequency depend on application with low power consumption. This paper presents a review the performance evaluation of different delay cell topologies the implemented in the ring oscillator. The various topologies analyzed includes current starved delay cell, differential delay cell and current follower cell. Performance evaluation includes frequency range, frequency stability, phase noise and power consumption had been reviewed and comparison of different topologies has been discussed. It is observed that starved current delay cell have lower power consumption and the different of the frequency range is small as compared to other type of delay cell

Carbonized rice husk and cocopeat as alternative media bed for aquaponic system

The study evaluates the suitability of carbonized rice husk and cocopeat substrates as alternative media bed in aquaponics unit for cultivation of red Nile tilapia and Gynura procumbens. Area occupied by the aquaponics unit is about 4.5 m2 and it was operated under equatorial climate conditions. Various substrates namely lightweight expanded clay aggregate (LECA), cocopeat, carbonized rice husk and a mixture of cocopeat-rice husk at ratio 1:1 were prepared using polybags for growing of the longevity spinach. The resultant effects from fish cultivation and plants growth on the water qualities and nitrification efficiency of the aquaponics unit were reported. The aquaponics unit were operated for twelve weeks and the values of pH, temperature, and dissolved oxygen level were measured to be within the range of 6.4-6.9, 27.7-29oC, and 5.5-7 mg·L-1, respectively. Survival rate for fish was 98% with specific growth rate (SGR) and food conversion ratio (FCR) of 6.9% per day and 1.13, respectively. Nutrient deficiency was not evident and plants showed healthy growth with harvest yield ranging between 3.6 and 3.9 kg·m-2. Results attained signified the suitability of utilizing carbonized rice husk and cocopeat as alternatives media bed compared to commercial media bed such as LECA

Production of biodiesel from palm fatty acid distillate by microwave-assisted sulfonated glucose acid catalyst

Biodiesel, one of the renewable energy sources has gained attention for decades as the alternative fuel due to its remarkable properties. However, there are several drawbacks from the industrial production of biodiesel such as the spike in the production cost, environmental issues related to the usage of homogeneous catalyst and profitability in long term. One of the solutions to eliminate the problem is by utilizing low cost starting material such as palm fatty acid distillate (PFAD). PFAD is a byproduct from the refining of crude palm oil and abundantly available. Esterification of PFAD to biodiesel will be much easier with the presence of heterogeneous acid catalyst. Most of acid catalyst preparation involves series of heating process using conventional method. In this study, microwave was utilized in catalyst preparation, significantly reducing the reaction time from conventional heating method. The catalyst produced was characterized using X-Ray Diffraction (XRD), Brunauer Emmet and Teller (BET), Scanning Electron Microscopy (SEM), Temperature-Programmed Desorption - Ammonia (TPD-NH3) and Fourier Transform Infrared (FTIR) while percentage yield and conversion of the PFAD were analysed by gas chromatography - flame ionization detector (GC-FID) and acid-base titration, respectively. It has been demonstrated that the percentage yield of biodiesel from the PFAD by employing sulfonated glucose acid catalyst (SGAC) reached 98.23% under the following conditions: molar ratio of methanol to PFAD of 10:1, catalyst loading of 2.5% and reaction temperature of 70oC. The microwave-assisted SGAC showed its potential to replace the SGAC produced via conventional heating method

Time-temperature superposition in viscous liquids

Dielectric relaxation measurements on supercooled triphenyl phosphite show that at low temperatures time-temperature superposition (TTS) is accurately obeyed for the primary (alpha) relaxation process. Measurements on 6 other molecular liquids close to the calorimetric glass transition indicate that TTS is linked to an $\omega^{-1/2}$ high-frequency decay of the alpha loss, while the loss peak width is nonuniversal.Comment: 4 page

Reliability of graphene as charge storage layer in floating gate flash memory

This study aims to investigate the memory performances of graphene as a charge storage layer in the floating gate with difference doping concentration of n-channel and p-channel substrates using Silvaco ATLAS TCAD Tools. The simulation work has been done to determine the performance of flash memory in terms of memory window, P/E characteristics and data retention and have been validated with the experimental work done by other researchers. From the simulation data, the trend of memory window at low P/E voltage is nearly overlapped between simulation and experimental data. The memory window at ±20V P/E voltage for n-channel and p-channel flash memory cell are 15.4V and 15.6V respectively. The data retention for the n-channel flash memory cell is retained by 75% (from 15.4V to 11.6V) whereas for the p-channel flash memory cell is retained by 80% (from 15.6V to 12.5V) after 10 years of extrapolation with -1/1V gate stress which shows that p-channel flash memory cell demonstrates better data retention compared to n-channel flash memory cell

INFLUENCE OF WATER AND PRECURSOR MOLARITY ON THE TiO2 THIN FILMS DEPOSITED FROM SOLVENTLESS SOL-GEL

Titania (TiO2) of anatase, anatase-rutile and anatase-brookite-rutile thin films were successfully established from sol-gel dip coating technique using titanium tetraisopropoxide (TTIP) as precursors without the presence of solvent. The thin films were deposited on glass substrate and the type of TiO2 crystalline structure produced was depending upon the molar ratio of the TTIP and water. Results shown that the TTIP molarity is more substantial in determining the TiO2 thin films crystallinity and crystallite size as compared to the water molarity. Meanwhile, the desired phases and crystallite size can be controlled by manipulating the molar ratio of water and TTIP. Thus, the establishment of the desired phases (anatase mixed rutile), crystallinity and crystallite size (anatase: 15 nm, rutile: 30 nm) of TiO2 thin films from solvent less sol-gel can be controlled and encouraging to explore as an effort toward producing a sustainable green photocatalytic material

Circularly polarized transmitarray antenna design using meander line polarizer for ku-band applications

In this paper, a circularly polarized Transmitarray antenna design for the Ku-band frequency range is presented. The transmitarray antenna with 121 elements is designed using a four-layer double square ring with a center patch unit cell. The Unit cell parametric analysis shows a high transmission coefficient magnitude of -1.26 dBi and a wide phase range of 256 degrees. A meander line polarizer is designed at 12GHz to convert the polarization from linear to circular. This meander line polarizer is placed in front of the horn antenna as a superstrate layer. The final measurement results show a high gain circular polarized TA antenna with a maximum gain of 20.17dBic and a value of 1.89 for the axial ratio is achieved at 11.2 GHz. The 1dB antenna gain and 3-dB axial ratio bandwidth are calculated as 0.65GHz and 1.07GHz, respectively. The proposed design offers a low profile and less complex structure, making it suitable for long-range communication systems, especially in Ku band applicati

Stress distribution and the fragility of supercooled melts

We formulate a minimal ansatz for local stress distribution in a solid that includes the possibility of strongly anharmonic short-length motions. We discover a broken-symmetry metastable phase that exhibits an aperiodic, frozen-in stress distribution. This aperiodic metastable phase is characterized by many distinct, nearly degenerate configurations. The activated transitions between the configurations are mapped onto the dynamics of a long range classical Heisenberg model with 6-component spins and anisotropic couplings. We argue the metastable phase corresponds to a deeply supercooled non-polymeric, non-metallic liquid, and further establish an order parameter for the glass-to-crystal transition. The spin model itself exhibits a continuous range of behaviors between two limits corresponding to frozen-in shear and uniform compression/dilation respectively. The two regimes are separated by a continuous transition controlled by the anisotropy in the spin-spin interaction, which is directly related to the Poisson ratio $\sigma$ of the material. The latter ratio and the ultra-violet cutoff of the theory determine the liquid configurational entropy. Our results suggest that liquid's fragility depends on the Poisson ratio in a non-monotonic way. The present ansatz provides a microscopic framework for computing the configurational entropy and relaxational spectrum of specific substances.Comment: 11 pages, 5 figures, Final version published in J Phys Chem

Dynamics of the rotational degrees of freedom in a supercooled liquid of diatomic molecules

Using molecular dynamics computer simulations, we investigate the dynamics of the rotational degrees of freedom in a supercooled system composed of rigid, diatomic molecules. The interaction between the molecules is given by the sum of interaction-site potentials of the Lennard-Jones type. In agreement with mode-coupling theory (MCT), we find that the relaxation times of the orientational time correlation functions C_1^(s), C_2^(s) and C_1 show at low temperatures a power-law with the same critical temperature T_c, and which is also identical to the critical temperature for the translational degrees of freedom. In contrast to MCT we find, however, that for these correlators the time-temperature superposition principle does not hold well and that also the critical exponent gamma depends on the correlator. We also study the temperature dependence of the rotational diffusion constant D_r and demonstrate that at high temperatures D_r is proportional to the translational diffusion constant D and that when the system starts to become supercooled the former shows an Arrhenius behavior whereas the latter exhibits a power-law dependence. We discuss the origin for the difference in the temperature dependence of D (or the relaxation times of C_l^(s) and D_r. Finally we present results which show that at low temperatures 180 degree flips of the molecule are an important component of the relaxation dynamics for the orientational degrees of freedom.Comment: 17 pages of RevTex, 12 figure