Far-infrared induced current in a ballistic channel -- potential barrier structure

We consider electron transport in a ballistic multi-mode channel structure in the presence of a transversely polarized far-infrared (FIR) field. The channel structure consists of a long resonance region connected to an adiabatic widening with a potential barrier at the end. At frequencies that match the mode energy separation in the resonance region we find distinct peaks in the photocurrent, caused by Rabi oscillations in the mode population. For an experimental situation in which the width of the channel is tunable via gates, we propose a method for reconstructing the spectrum of propagating modes, without having to use a tunable FIR source. With this method the change in the spectrum as the gate voltage is varied can be monitored.Comment: Submitted to Phys. Rev.

CANONICAL QUANTIZATION OF DISSIPATIVE SYSTEMS

The canonical method is invoked to quantize dissipative systems using the WKB approximation. The wave function is constructed such that its phase factor is simply Hamilton’s principal function. The energy eigenvalue is found to be in exact agreement with the classical case. To demonstrate our approach, the three examples considered in our previous work (ESJ 9(30), 70-81, 2013) are quantized in detail: the damped harmonic oscillator, a system with a variable mass, and a charged particle in a magnetic field

A HAMILTON-JACOBI TREATMENT OF DISSIPATIVE SYSTEMS

Dissipative systems are investigated within the framework of the Hamilton-Jacobi equation. The principal function is determined using the method of separation of variables. The equation of motion can then be readily obtained. Three examples are given to illustrate our formalism: the damped harmonic oscillator, a system with a variable mass, and a charged particle in a magnetic field

AN ASSESSMENT OF THE STATUS OF SMALL RICE THRESHERS IN NIGERIA

An assessment of existing rice thresher designs and products available within Nigeria and neighbour-         ing countries was carried out. The impetus for the study is the concern that low and poor quality of         local rice in Nigeria may be due, in important measure, to lack of appropriate and affordable small        threshers. On this basis, a reconnaissance work in Five Local Government Areas in Ogun State,    Erin        – Ijesha in Osun State, Igbimo in Ekiti State; Abakaliki in Ebonyi State, Makurdi in Benue State as well        as   Kura  -  Kano   and   Tundun   Wada   areas   of   Kano   State   was   carried   out.   Based   on   the   farmers’        evaluation   and   assessment   of   existing   rice   threshers   available   in   Nigeria,   the   study   recommended        three prototype small threshers that are pedal and petrol engine driven. The pedal operated thresher        was recommended for those with farm hectarage of less than 2. For threshing freshly harvested rice at        very   high   moisture   content,   the  IITA/WARDA   small   plot   spike-tooth   thresher   which   has   a  threshing        capacity of about 100kg/h was found to be appropriate for the small – scale farmers provided some         little modifications in the area of capacity and mobility were carried out while the multi-crop thresher of        the Institute of Agricultural Research and Training (IAR&T) Ibadan with a capacity of about 250kg/h        was recommended for those with farm hectarage of more than 5ha.&nbsp

DEVELOPMENT OF A MANUALLY OPERATED DOUGH DICING MACHINE FOR COLD EXTRUSION

The timely production of diced dough for the final preparation of chin-chin (a confectionery made of fried dough) have not witnessed any substantial development among the women folk that engaged in such activities in Nigeria. A manually operated dough-dicing machine was designed and developed for the timely production of diced dough. The dough dicer offers a better method of dicing dough into various desired shapes and lengths, which may not be possible with the existing processing method. Preliminary test of the manually operated dough dicer showed that a minimal pressure of 4473.122 Pa is sufficient to force out the dough through the die outlet. The low cost dough dicer requires the minimum manual power input of 0.16 Watt for the dicing of the dough with a density of 1126.4 Kg/m3. The overall performance of the manually operated dough dicer showed that the machine would be of great benefit to the small scale producers of the confectionery

MOISTURE DEPENDENCE OF SOME AERODYNAMIC PROPERTIES OF BENISEED

Some aerodynamic properties of two varieties of beniseed (Yandev 55 and E8) were determined at        moisture content levels of 5.3, 10.6, 16.1 22.4, 28.3 per cent (wet basis). The determined properties        were particle diameter, frontal area, terminal velocity and drag coefficients. A - 2 x 5 factorial experi-        ment in Completely Randomized Design with a total of 30 observations was used for each of the pa-        rameters. The particle diameter and frontal area increased from 1.52 to 1.78mm and 1.77 to 2.49 mm2        for Yandev 55; 1.74 to 2.18 mm and 2.38 to 3.73 mm2    for E8 respectively as the moisture content        increased from 5.3 to 28.3%.  The respective terminal velocities decreased from 3.05 to 2.74m/s and        2.80 to 2.48m/s for Yandev 55 and E8 within the studied moisture content levels. Increasing the mois-        ture content from 5.3 to 16.10% increased the drag coefficient from 2.67 to 2.70 and 2.74 to 2.78 for        the two accessions respectively. A further increase to 22.4% decreased the respective values to 2.64        and 2.61. The effect of moisture content on beniseed was highly significant on the terminal velocity.&nbsp

On the bifurcation diagram of the capillary-gravity Whitham equation

We study the bifurcation of periodic travelling waves of the capillary-gravity Whitham equation. This is a nonlinear pseudo-differential equation that combines the canonical shallow water nonlinearity with the exact (unidirectional) dispersion for finite-depth capillary-gravity waves. Starting from the line of zero solutions, we give a complete description of all small periodic solutions, unimodal as well bimodal, using simple and double bifurcation via Lyapunov--Schmidt reductions. Included in this study is the resonant case when one wavenumber divides another. Some bifurcation formulas are studied, enabling us, in almost all cases, to continue the unimodal bifurcation curves into global curves. By characterizing the range of the surface tension parameter for which the integral kernel corresponding to the linear dispersion operator is completely monotone (and therefore positive and convex; the threshold value for this to happen turns out to be $T = \frac{4}{\pi^2}$, not the critical Bond number $\frac{1}{3}$), we are able to say something about the nodal properties of solutions, even in the presence of surface tension. Finally, we present a few general results for the equation and discuss, in detail, the complete bifurcation diagram as far as it is known from analytical and numerical evidence. Interestingly, we find, analytically, secondary bifurcation curves connecting different branches of solutions; and, numerically, that all supercritical waves preserve their basic nodal structure, converging asymptotically in L^2(\SM) (but not in $L^\infty$) towards one of the two constant solution curves

Background radiation dose of dumpsites in Ota and Environs

In-situ measurement of background radiation dose from selected dumpsites in Ota and its environs was done using Radialert Nuclear Radiation Monitor (Digilert 200). Ten measurements were taken from each dumpsite. The measured background radiation range between 0.015 mRhr-1 for AOD and 0.028 mRhr-1 for SUS dumpsites. The calculated annual equivalent doses vary between 1.31 mSvyr-1 for AOD and 2.28 mSv/yr for SUS dumpsites. The air absorbed dose calculated ranged from 150 nGyhr-1 to 280 nGy/hr for AOD and SUS dumpsites respectively with an average value of 217 nGyhr-1 for all the locations. All the estimated parameters were higher than permissible limit set for background radiation for the general public. Conclusively, the associated challenge and radiation burden posed by the wastes on the studied locations and scavengers is high. Therefore, there is need by the regulatory authorities to look into the way and how waste can be properly managed so as to alleviate the effects on the populace leaving and working in the dumpsites vicinity

Comparative Evaluation of Antioxidant Properties of Methanol Extracts of Allium cepa bulb, Allium cepa bulb peels and Allium fistulosum.

Medicinal plants have protective effects against many physiological diseases because of their phytochemical components which are better antioxidants. This study was aimed at comparing the in vitro antioxidant activity, phenolic and flavonoid content of the methanol extracts of Allium cepa bulb, Allium cepa bulb peel and Allium fistulosum. The antioxidant activity was determined by 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity, ferric reducing antioxidant power (FRAP), iron chelating activity and molybdate ion reduction assays. The total flavonoid and total phenolic content (TPC) were carried out using aluminium chloride and Folin-Ciocalteu assay respectively. The results showed that A. cepa bulb peel has the highest phenolic content and the antioxidant activity while the A. fistulosum showed the least. Furthermore, the total flavonoid content and metal iron chelating activity was highest in A. cepa bulb, while lowest values were obtained in A. fistulosum and A. cepa bulb peel respectively. The results suggest that the A. cepa bulb peel, A. cepa bulb and A. fistulosum extracts can be used as sources of natural antioxidants. However, A. cepa bulb peel may be the most potent

Optimality of broken extremals

In this paper we analyse the optimality of broken Pontryagin extremal for an n-dimensional affine control system with a control parameter, taking values in a k- dimensional closed ball. We prove the optimality of broken normal extremals when n = 3 and the controllable vector fields form a contact distribution, and when the Lie algebra of the controllable fields is locally orthogonal to the singular locus and the drift does not belong to it. Moreover, if k = 2, we show the optimality of any broken extremal even abnormal when the controllable fields do not form a contact distribution in the point of singularity.Comment: arXiv admin note: text overlap with arXiv:1610.0675