Horizontal Storage Research Articles

INVESTING IN GRAIN STORAGE FACILITIES UNDER FLUCTUATING PRODUCTION*

Fluctuating annual harvest volumes create a peak load problem in the provision of grain storage capacity. There are a number of technologies for handling and storing grain, ranging from capital intensive to labour intensive methods. Optimal provision of grain storage capacity can therefore be analysed in the framework of the conventional peak load pricing model. An investment model of grain storage is outlined and the optimal technology choices are determined according to simple investment roles. Capacity of the more capital intensive storage types should be only provided if the extra capital cost is justified by the saving in operating costs, which depends on the expected utilisation of storage. Some level of supply failure is justifiable. An examination of grain storage costs in Western Australia revealed that horizontal storage was the best technology for dealing with most grain storage demand at sites where turnover is limited In the receival period. This concurs with the general investment choices in Western Australia. However, there appears to be a high level of overcapacity at many sites, implying that the cost of supply failure is perceived to be greater than the marketable value of the grain.

A 2-million-pixel CCD image sensor overlaid with an amorphous silicon photoconversion layer

A highly sensitive 2-million-pixel high-definition charge-coupled device (CCD) image sensor was developed that features an overlaid amorphous silicon photoconversion layer on an interline transfer-type CCD scanner. The device is adapted to the 16:9 aspect ratio. 1125 scanning lines and 2:1 interlace high-definition TV system. A dual-channel horizontal CCD register is used to reduce the operating frequency to one half of the 74.25-MHz readout frequency. A horizontal period signal storage memory (1H line memory) is provided between the vertical CCD register and the horizontal CCD register to provide the signal distribution from the vertical CCD to the horizontal CCD register during the 3.77- mu s short horizontal blanking interval. This device realized a 1000 TV line horizontal limiting resolution 210 nA/1x high sensitivity. Total random noise was found to be 52 electrons RMS and a 72-dB dynamic range was achieved. >

The thermal behaviour of thin cylindrical shells—II: Elastic thermal stress analysis

The double Fourier series thermal stress solution is presented. This is based on Sanders' linear shell theory with additional thermal loading terms. These arise due to a mid-surface temperature distribution and due to the temperature difference between the inside and outside surfaces. The thermal loading is represented by double Fourier coefficients which are determined by harmonic analysis from the temperature distributions obtained from heat transfer models, numerical techniques or measurement. The examples investigated are those analysed in Part I ( Int. J. Mech. Sci. 31, 693–706, 1989) of this paper, namely, a circular hot spot in a high-temperature cylindrical reactor vessel and the solar heating of a horizontal storage vessel. The stress solutions obtained in these cases are compared with finite element results. The method is quick and easily programmable and, as an integrated package, is particularly suitable for evaluating the effect on the stress levels of possible heat transfer conditions.

The thermal behaviour of thin cylindrical shells—I. Heat transfer and harmonic analysis

The combined heat transfer and thermal stress analysis of thin cylindrical shells is considered in this and a subsequent paper. This paper presents two typical heat transfer models and the harmonic analysis which is used to represent the temperature distributions as double Fourier coefficients. These models are (i) a circular hot spot caused by a postulated loss of part of the internal refractory lining in a high temperature cylindrical reactor vessel and (ii) a heated “band” caused by solar heating on a horizontal storage vessel. In the case of the hot spot the inside and outside surface temperature distributions vary independently in the axial and circumferential directions, with linear transition through the thickness. In the simpler case of solar heating, the through-thickness temperature gradient is negligible and the temperature only varies around the circumference. The use of the double Fourier coeficients to obtain the displacements and stresses is described in Part II

Effect of active head movements about the pitch, roll, and yaw axes on human optokinetic afternystagmus.

Effects of active head movements about the pitch, roll, or yaw axes on horizontal optokinetic afternystagmas (OKAN) were examined in 16 subjects to test the hypothesis that otolith organ mediated activity induced by a change in head position can couple to the horizontal velocity storage in humans. Active head movements about the pitch axis, forwards or backwards, produced significant OKAN suppression. Pitch forward head movements exerted the strongest effect. Active head movements about the roll axis towards the right also produced OKAN suppression but only if the tilted position was sustained. No suppression was observed following sustained yaw. However, an unsustained yaw left movement after rightward drum rotation significantly enhanced OKAN. Sustained head movement trials did not significantly alter subsequent control trials. In contrast, unsustained movements about the pitch axis, which involve more complex interactions, exerted long-term effects on subsequent control trials. We conclude that otolith organ mediated activity arising from pitch or roll head movements couples to the horizontal velocity storage in humans, thereby suppressing ongoing OKAN. Activity arising from the horizontal canals during an unsustained yaw movement (observed mainly with yaw left), following drum rotation in a direction contralateral to the movement, may also couple to the velocity storage, resulting in increased activity instead of suppression.

Temperature changes in bulk stored wheat in sub-tropical Australia

A simple simulation model is presented to describe temperature changes observed during summer and autumn in three grain bulks in horizontal storages in the sub-tropical region of Australia. The model includes empirical descriptions of temperatures of upper and lower surfaces and finite difference equations describing heat transfer by conduction. Although the model is simplistic it should prove useful as a predictive tool for entomological purposes. Predicted temperatures closely followed observed temperatures. Grain temperatures 2 m from the surface changed little during summer and autumn, and remained favourable for insect development at the start of winter. In one storage, heating associated with a heavy insect infestation raised temperatures to over 40°C.

The behaviour of a horizontal vessel on loose saddles — a buckling assessment of the support region

By using two computer-based buckling programs, NASTRAN and BOSOR4, the buckling behaviour of the support region of six horizontal storage vessels is assessed. The vessels are supported on twin saddles shown in Fig. 1(a) and of diameter/thickness ratios from 312 to 1154, and lengih radius ratios from 4 to 6.5. They were chosen to provide a range of typical vessels in present use. The specific gravity of the liquid contents required to cause buckling in the support region was obtained by using the computer programs and also by using an equivalent cylinder length with the existing formulations given in the British Pressure Vessel Code, BS 5500 for axisymmetric loading. Comparison of these approaches is used to validate a procedure for finding an allowable buckling stress, hitherto not available for this component.

Accelerated rooting of carnation ‘Red Baron’ by temperature pre-treatment

Rooting of carnation cuttings was promoted by storage temperatures above 0°C with an inverse relationship between the level of temperature and the duration of the treatment. The effect of temperature on root dry weight was far more important than the effect of duration of storage. A long storage and a high temperature increased the incidence of Fusarium. Storage at temperatures lower than 13°C gave better results with auxin applied after storage, while temperatures higher than 13°C gave better results with a pre-treatment of auxin. During storage for 14 days at 9°C, the position of the cuttings had no clear effect on rooting. Horizontal storage, however, appeared to be unfavourable. Removal of 0.5 cm of the base of the stem after storage nullified the storage effect. Carbohydrates in the removed pieces decreased during storage, more so at 13°C than at 0°C. Anatomically, an acceleration of cell division at the base of the cutting was observed during storage at 9°C as compared to 0°C. At a commercial nursery, storage of cuttings for 12 days at 14°C improved rooting by 84% compared to storage at 0°C. The presented technique tends to shorten the expensive and vulnerable period from planting to rooting.

A study of the stability of horizontal cylindrical vessels filled with varying amounts of liquid— Part I: Experimental investigations

The instability behaviour of thin-walled horizontal cylindrical vessels supported by means of ring girders, or from rigid end plates, is examined experimentally during liquid filling. Selected results from a horizontal test on a large stainless steel horizontal storage vessel are presented to illustrate the way in which thin-walled vessels, of large radius/thickness ratios (300–650), behave during fill. Such results have provided the motivation for some 26 polyester film model cylinder tests. The models cover three different radius/thickness ratios (300, 400 and 500) and a range of length/radius ratios. They were supported at their ends and progressively filled with liquid. In each case the onset of instability was noted. In Part II 1 of this paper a theoretical approach is presented and compared with the experimental values in an effort to assess the validity of design methods currently in use.

Stresses in horizontal storage vessels - a comparison of theory and experiments

This paper presents the salient features of the experimental work carried out on a series of horizontal storage vessels. These include a 3.66 m diameter gas receiver and two smaller vessels each of 0.91 m diameter. The saddles used to support the vessels represent the two extremes of saddle design where the cantilever section is either of ‘flexible’ or ‘rigid’ construction and in both cases welded to the vessels. All the vessels were extensively strain gauged in the region of the saddle supports and at the centre of the vessel. Hydraulic, pressure surcharge and pneumatic tests were carried out on the vessels. Typical experimental results have been compared with the theoretical analysis described in (1)†. It is found that a satisfactory measure of agreement is obtained for both the flexible and more rigid results for the water fill tests, but that the pressure results are sensitive to vessel imperfection which are not considered in the theoretical analysis (1).

An Investigation of Thermal Stratification in Horizontal Storage Tanks

The thermal behavior of a horizontal storage tank has been investigated numerically and experimentally. The purpose of the present work is to compare a simple, one-dimensional model to the measured temperature stratification in this horizontal tank. For the test conditions used in these experiments, axial temperature gradients were found to be negligible compared to vertical temperature gradients. It was observed that significant mixing of the tank occurred when water was removed unless a diffuser manifold was placed on the makeup water inlet. The numerical model used was one-dimensional (vertical) with some degree of mixing at the inlet and outlet boundaries. The temperatures at the top of the tank were predicted fairly well, but the temperatures at the bottom deviated somewhat from the predictions. It appears that some additional interior mixing, not included in the present model, occurs.

Precipitation Flux Climatology of the Free Atmosphere

Abstract The diabatic heating of the atmosphere can be very closely represented by the convergence of a vertical energy flux. It consists of two components: the flux of net radiation and the flux of precipitation. The latter comprises the vertical flux of water in condensed form (rain, snow, ice). The concept of precipitation flux is investigated employing the zonal mean equation of potential heat. Input data are radiation flux from a model, adjusted at the top and bottom of the atmosphere with observed data; horizontal advective heat flux convergence and heat storage with the data of the MIT Library; and vertical sub-synoptic eddy flux of sensible heat (a small quantity) from a parameterization. Output is the precipitation flux in the free atmosphere. Time scale is 1 month, space domain is the zonal mean Northern Hemisphere. The precipitation flux is downward everywhere. It is maximum in the tropics. Comparison of the flux across the 1000 mb level with the observed surface precipitation shows satisfactor...

HOMOGENEITY OF CARBON DIOXIDE/OXYGEN MIXTURES

SUMMARY In order to overcome the costs of buying cylinders of carbon dioxide/oxygen gas mixtures for use with the micro-Astrup apparatus the problems of inhomogeneity were investigated in laboratory-produced cylinders. It was noted that filling pressure seemed to be related to the duration of mixing. At 1300 Lb./sq.in. long periods of vertical or horizontal storage were required after vertical filling unless rolling was used. Filling in the horizontal or inverted positions with storage for 30 min in the same position proved satisfactory.