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During the rice harvesting process of combine harvester, it is necessary to adjust the working parameters of the threshing device in time according to working conditions to ensure operational efficiency and performance. This paper designs a variable diameter threshing drum, develops a device for diameter regulation with self‐locking function, and its installation process and working principle are introduced in detail. A force analysis and modal analysis were carried out on the device for diameter adjustment of variable diameter threshing drum. It aims to ensure that the design dimensions of the constant speed spiral disc and claws in the device for diameter adjustment are in compliance with the self‐locking conditions, and effectively ensure the reliability of the device for diameter adjustment. A field experiment was carried out to check the reliability of the developed system. A regression analysis model takes the feeding rate, threshing gap and drum speed as influencing factors. The grain separation loss rate and damage rate as performance indexes were established, and calculations for multiple target optimization were performed. The experimental results showed that the threshing gap could be adjusted in real time according to the different feeding rates of the variable diameter threshing drum., This paper develops a threshing drum with variable diameter making it possible to adjust the drum diameter integrally and quickly. The developed device can provide a reference to design of threshing drum with variable diameter as well as that of self‐adaptive control system.

OBJECTIVES. Conventional reporting of posttympanoplasty hearing outcomes use a pure-tone averaged air-bone gap (ABG) largely representing a low-frequency sound conduction. Few studies report high-frequency conductive hearing outcomes. Herein, we evaluate high-frequency ABG in patients following temporalis fascia total drum replacement. STUDY DESIGN. Case series with chart review. SETTING. Tertiary care center. SUBJECTS AND METHODS. All patients who underwent type 1 tympanoplasty using a lateral graft total drum replacement technique between August 2016 and February 2019 were identified. Patients with pre- and postoperative audiograms were included. Low-frequency ABG was calculated as the mean ABG at 250, 500, and 1000 Hz. High-frequency ABG was calculated at 4 KHz. Pre- and postoperative ABGs were compared. RESULTS. Twenty-three patients were included, and the mean age at surgery was 44 years (range, 9–68 years). Perforation etiology was from trauma (n = 14) or chronic otitis media (n = 9). Preoperative mean low-frequency ABG was 27.8 ± 12.6 dB and mean high-frequency ABG was 21.5 ± 15.1 dB (P = .044). Postoperatively, the mean low-frequency ABG was significantly reduced by 15.5 ± 13.3 dB (P < .001) while the mean high-frequency ABG insignificantly changed (reduced by 2.6 ± 16.2 dB, P = .450). CONCLUSION. In a series of patients undergoing temporalis fascia total drum replacement, low-frequency ABG improved; however, high-frequency conductive hearing loss persists. Conventional methods of reporting ABG may not identify persistent high-frequency ABG. These results merit further study across a range of tympanoplasty graft materials and surgical techniques.

The South Carolina Department of Natural Resources (SCDNR) began stocking red drum, Sciaenops ocellatus (Linnaeus), in 1989 to augment the abundance of juveniles available for recreational harvest in South Carolina estuaries. While stock enhancement can help supplement wild populations under high fishing pressure, releasing hatchery‐raised fish into the wild also presents the risk of decreased genetic diversity. An individual‐based model (IBM) was developed to forecast the genetic influences of stocking on the wild spawning population to inform responsible stocking strategies. Model results indicated the SCDNR red drum stock enhancement programme should maintain mean contributions of stocked fish no greater than 30% per year class over a 45‐year stocking period, coupled with at least 10 effective breeders in the hatchery replaced annually, to maintain current levels of genetic diversity estimated in the wild population. The IBM is a useful tool for hatchery managers to guide responsible stock enhancement.

International audience; This paper presents a theoretical description of a particle motion in a rotary dryer equipped with straight lifters distributed on its periphery. In this configuration, the transport of granular materials occurs with cyclic cascades that can be decomposed into three phases: lifting, discharging, and falling into the air stream. In order to describe each of these phases, we have focused on the motion of a single particle in a rotating drum. In this condition, the analytical solution of the motion equation of each phase is found. With these solutions, the position and the velocity of the particle at any time are thus expressed as a function of physical parameters of the particle, physical parameters of the drum, and physical parameters of air in the drum, called operating parameters in practice. With these equations, we are able to calculate the behaviour of the particle as a function of the operating parameters. The transposition to the industrial context is made with an application. We show how these equations particularly permit the estimation of the Mean Residence Time (MRT) of material during the drying process as a function of operating parameters. Such estimations have been validated by comparison with experimental data of MRT found in the literature. The work presented in this paper gives some useful mathematical relations for whose who are interested in drum design optimization (lifter length, drum radius, drum length, etc.). More specifically, they can be used to help with the choice of operational parameters values that would achieve a given value of MRT for particular product.

Many species perform social displays that incorporate complex body movements. However, the reason why such exaggerated behavioural signals evolve in the first place is unclear. Recent work posits that physical displays arise in part because they showcase an animal's motor skill—that is, the ability to produce challenging motor acts with great coordination, precision and/or speed. Support for this idea is largely correlational, with few studies attempting to manipulate metrics of motor skill to assess their effect on physical display efficacy. Here, we address this issue in the downy woodpecker (Dryobates pubescens). Individuals of this species compete for territories through the performance of drums, which are complex displays produced by rapidly hammering the bill against a resonate surface at rates of 16 hits/s. This display is a whole-body endeavour, and its production relies on the ability to swiftly oscillate the head forward and backward at fraction-of-a-second periods. Using a series of playback studies, we expose resident birds to experimentally engineered drums that reflect putative fine-scale differences in the motor command of the head and neck. We show that resident individuals respond more aggressively to drums characterized by a cadence with a 9-ms faster beat speed. These residents even modulate their own drum speed to resemble this high-performance stimulus, although they often fail to reach it. Residents also appear to appraise drum acceleration by listening to the time intervals between successive beats in a single drum, while tracking how these time intervals change as the signal progresses. Our data support a connection between motor skill and the effectiveness of a physical display produced through elaborate body movement. We, therefore, suspect that motor skill is adaptive and evolves in response to selection by competition for effective drum displays. A plain language summary is available for this article.

Brazil is the largest producer and exporter of coffee in the world, one of the main global commodities. During the processing of coffee beans, rotary drums are used in the drying and roasting phases. This equipment is widely used in many industrial sectors. According to characteristics of the drum, particulate material, and operating conditions, different flow regimes may arise. Such regimes have a direct influence on the performance of these processes and therefore their characterization is of great importance. The present work developed an experimental study about the dynamics of coffee beans, under green and roasted conditions, in a rotary drum. Transitions between rolling, cascading, cataracting, and centrifuging regimes were evaluated, for both green and roasted coffee beans. For the centrifuging regime, a comparison between experimental critical rotation speeds and the ones obtained by correlations found in literature was performed. Additionally, a new expression to predict the centrifuging rotation speed was proposed by the authors. Further analyses regarding the rolling regime were also carried out. For this regime, velocity profiles of the particles were evaluated, as well as the thickness of the active layer for different filling degrees and drum rotation speeds. Great similarity was found between the behaviour of the active region for coffee beans before and after the roasting process.

This paper involves an experimental and numerical study on the grinding media dynamics inside a baffled ball mill under different solid flow regimes: cascading, cataracting and centrifuging. The Eulerian approach was used for all simulations and the boundary condition at the drum wall was investigated by means of the specularity coefficient parameter. This effort presents a meaningful temptation in representing the particle-wall interaction in a ball mill. The balls restitution coefficient was experimentally measured using a video camera, and its influence was evaluated by comparing the numerical and experimental outcome of flow patterns. The simulations results showed that the specularity and restitution coefficients effects at the drum wall were more evident at high rotation speeds.

The effect of particle aspect ratio on the rheology of the flow of granular materials is studied experimentally in a quasi-two-dimensional rotating cylinder, using two varieties of prolate spheroidal grains with different aspect ratios. Image analysis of high speed videos is used to obtain the flow profiles near the centre of the cylinder. The dynamic angle of repose and apparent viscosity in the medium show significant increase with increasing aspect ratio. The mean velocity, root mean square velocity and shear rate profiles are qualitatively similar for nonspherical and spherical particles, however, their magnitudes increase with increasing aspect ratio. A simple scaling is shown to predict the maximum thickness of the flowing layer for all the particles. The predictions of a model for the flow match with the measured mean velocity profiles and layer thickness. (c) 2017 American Institute of Chemical Engineers AIChE J, 63: 4307-4315, 2017

This study investigates how the drum-to-particle diameter ratio (D/d) affects the surface speed and interparticle coating variability in geometrically similar coaters. Discrete element method simulations were used to model particle movement in different-sized, cylindrical drums with identical particle diameters, Froude numbers, fill volume fractions, and spray characteristics. The dimensionless streamwise surface speed profiles become increasingly symmetric as D/d increases, with the maximum speed increasing with D/d. The relationship between the maximum dimensionless speed and D/d is fit well with a power-law expression. Interparticle coating variability decreases with the square root of the number of drum revolutions after a sufficiently large number of drum revolutions. Increasing D/d increases, in a logarithmic manner, the number of drum revolutions required to reach a given degree of coating variability. A similar logarithmic coating variability trend was observed in simulations using almond-shaped pharmaceutical tablets, suggesting that the trend is independent of tablet shape. © 2017 American Institute of Chemical Engineers AIChE J, 63: 3743–3755, 2017

In this study, a model is carried out to investigate heat transfer within granular system in the novel flighted rotary drum (FRD). The model using Eulerian continuum approach (ECA) is developed and then verified by comparing with experimental data published previously. The effects of flight configuration, number of flights, rotational speed and fill level on heat transfer characteristics are discussed. The results show that increasing rotational speed can intensify heat transfer in a certain degree, but it is not significant. The average temperature of granular materials increases with the increase of the number of flights and the decrease of the fill level. More importantly, the average temperature is strongly dependent on flight configurations (including different length ratios and flight tip angles). There is an enhancement in heat transfer when the length ratio S1/S2 is 1 or the flight tip angle is higher. This article is protected by copyright. All rights reserved

The dangerous goods regulations UN/ADR 6.1.5.5.4 (a) prescribe a maximum filling degree for determining the test pressure for the hydraulic pressure test by real measurements. The assumption is that the maximum filling degree of the liquid phase is the worst case concerning the gauge pressure. Therefore, the main objective of this study is to investigate the effect of the filling degree on the gauge pressure. Gauge pressure measurements and calculations for different substances were carried out at different filling degrees for a steel drum and a steel jerrican (heating up from 15°C to 55°C). The assumption that the maximum filling degree is the most critical is only valid for relatively rigid packagings: If the relative expansion of the packaging is smaller than the volume increase of the liquid phase due to heating up, the gauge pressure increases with increasing filling degree. But the opposite is true for relatively flexible packagings: If the relative expansion of the packaging exceeds the relative volume expansion of the liquid, the gauge pressure increases for decreasing filling degrees. The current regulations for the hydraulic test pressure determination at a maximum filing degree do not lead to the intended safety level. For a lower level than the maximum filling degree, the prescribed safety factor of 1.5 is not respected. Under transport conditions, it is possible that the inner gauge pressure exceeds the test pressure. This can result in a failure of the packaging. There is a need to reconsider the regulations. Copyright © 2016 John Wiley & Sons, Ltd.

Sounds produced by the Shi drum Umbrina cirrosa were short trains of pulses with an average pulse period of 180 ms, pulse duration of c. 40 ms and an average peak frequency of 400 Hz; average values of acoustical properties differed from those recorded from the brown meagre Sciaena umbra in previous studies. The present study provides a preliminary tool for discriminating between these two species while conducting passive acoustic monitoring. The potential effects of ontogeny on sound production in both species are discussed and recommendations are made for further research.

The quality of individuals released from fish culture facilities for stock enhancement can affect success in achieving management goals. However, the quality of released individuals is not always known, and neither are the various aspects of aquaculture that influence fish quality. Quality or body condition at multiple life stages may be influenced by density-dependent impacts on growth. Here, the influence of stocking density (number of larvae per cubic meter) at the beginning of pond culture and harvest density at the end of pond culture were assessed in relation to growth and body condition using data from 121 stock enhancement culture ponds for Red Drum Sciaenops ocellatus. While stocking density did not influence Red Drum growth rate, harvest density was a reliable predictor of growth; high density at harvest resulted in slow growth in weight (r2 = 0.33, P < 0.001) and length (r2 = 0.26, P < 0.001). No negative impacts on pond yield were observed in ponds stocked over the targeted stocking ra...

The Black Drum Pogonias cromis is an estuarine-dependent fish that supports recreational and commercial fisheries throughout its range along the U.S. Atlantic coast and Gulf of Mexico (GOM) coast. We used nuclear microsatellite markers and samples collected from multiple locations along both the U.S. Atlantic and GOM coasts to evaluate the stock structure of Black Drum and to examine small-scale spatial genetic population structure along the U.S. Atlantic coast. As no microsatellite primers had been developed for Black Drum, primers for Spotted Seatrout Cynoscion nebulosus and Red Drum Sciaenops ocellatus were screened, selected, and optimized for use with Black Drum DNA. Six polymorphic loci were identified and used to genotype samples. Results suggested (1) significant genetic divergence between Black Drum populations from the U.S. Atlantic coast and the GOM coast; and (2) either recent or current gene flow between the two regions. Along the U.S. Atlantic coast, there appeared to be weak but sig...

The objective of this work was to determine the maximum gauge pressure in the vapour phase above the liquid in different design types of dangerous goods packagings under normal conditions of carriage. The design types investigated were steel and plastic packagings with a volume of approximately 6 l. Two different methods were applied. In method 1, the pressure inside the packaging filled with a certain filling substance (dichloromethane) was directly measured under simulated conditions of carriage (degree of filling: 90%; filling temperature: 15°C; temperature during storage: 31°C). The maximum measured gauge pressures were between 89 mbar for a light plastic jerrican and 336 mbar for a steel drum. In method 2, the gauge pressure was calculated. The consideration of a rigid packaging combined with the assumption of a vapour pressure of zero during filling and sealing can serve as a worst case scenario. The calculated gauge pressure is approximately 1061 mbar. This procedure leads to the highest safety factor and does not require any experimental investigations. For a more realistic approximation of the gauge pressure of a non-rigid packaging, a packaging-specific function of relative expansion can be used, which is determined by a hydraulic pressure test. The calculated values ranged from 105 to 347 mbar. Method 2 provides conservative results. No hazardous filling substance is needed, and it allows a prediction of gauge pressure for other temperatures, substances and filling degrees. Therefore, this method could serve as alternative to UN Model Regulations 6.1.5.5.4 (a). Copyright © 2014 John Wiley & Sons, Ltd.

Tubular scaffolds with controllable fiber orientations are fabricated by electrospinning with a conductive rotating drum in the presence of a parallel or orthogonal conductive wire. A higher rotational speed of the drum results in thinner fibers and a more aligned fibrous structure. The fiber orientation can be further precisely controlled by the design of a conductive wire capable of guiding the deposition of electrospun fibers. Parallel or orthogonal fiber orientations in the tubular scaffolds are achieved using an orthogonal or parallel conductive wire, respectively, at a high rotational speed of the drum. Cell culture on the scaffolds with random, parallel, and orthogonal fiber orientations reveals that the degree of stretching of the fibroblast is highly affected by the fiber orientations.

The importance of defining and quantifying ontogenetic movements and connectivity between juvenile and adult fish populations, especially for exploited species, has been well documented. Furthermore, the persistence of strong year-classes can be used to track the success of regulations that contribute to the increased survival and escapement of fish into the adult population. Size and age structures of Red Drum Sciaenops ocellatus were documented within the Tampa Bay estuary, in southwest Florida, using haul seines and trammel nets (1989–2008), and in nearshore Gulf of Mexico waters using a commercial purse seine (2005–2008). In the estuary, juvenile Red Drum ( 800-mm TL) were rare. Red Drum from nearshore gulf waters ranged from 2 to 35 years of age (674–1,074-mm TL), but most were greater than age 4. After back-calculating ages from Re...

This paper discusses the three phases of the lifecycle of the bojale drum: its custodianship by the queen of Bakgatla-baga-Kgafela; the drum's use in bojale (girls’ initiation ceremony); and its presence in Phuthadikobo Museum, a community institution. This lifecycle was observed by the author prior, during, and post initiation in bojale, a girls’ initiation school in 2009. The drum's use, its royal significance and sacredness, is barely documented in its museum record, which can result in its misinterpretation. The recommendations are that the drum's documentation, preservation, handling, and storage in the museum should incorporate its intangible cultural attributes if the museum is to be relevant to the Bakgatla-baga-Kgafela community. In conclusion, bojale drum is an example of how material culture can connect a museum with its community through the living culture of bojale.

Rapid urbanization and improvement in living standard skyrocket the demand for washing machines in Chinese households, especially in urban households. This paper discusses the owning rate of different types of washing machines, using frequency, load capacity, factors affect choices of washing machines, etc. in Chinese households and suggest possible strategies in choosing washing machines considering economic expenditure. Quantitative information relates to choice and use of household washing machines was collected through in-depth interview of the key person who carried out household laundering. A total of 993 households that were randomly selected in eight provinces and a municipality were successfully interviewed. Impeller washing machine is still in a dominate place whereas drum washing machine increasing steadily. Households with higher income tend to buy drum washing machines for their better performances in detergency and superior quality. Load capacity between 4 and 6 kg is very common at present. Larger load capacity is a trend of washing machine choices in Chinese households. Washing machine with better energy efficiency is more popular for its lower expenditure in use. This is more obvious for drum washing machine. Washing machines are often used once every 1 or 2 days in summer, whereas one wash per week and two washes per week are very common in winter. Consumer will expend much more money with the choice of a drum washing machine, not only for paying for the machine, but also for the consumed electricity and water and wastewater discharges in every use.

Climate–growth relationships of fish are of increasing research interest. However, few studies have attempted to characterize the extent to which climate–growth relationships may diverge across fundamentally different types of environments. The goal of this study was to examine the effects of climate variability (i.e., temperature, precipitation, global climate indices) on the growth of Freshwater Drum Aplodinotus grunniens and determine the extent to which these relationships differ between lotic and lentic habitats. Freshwater Drum were collected from five river and five reservoir environments in Georgia, Alabama, and Mississippi. Tree-ring techniques were used to standardize annual growth for age (measured using interannual growth increments from otolith sagittae) and growth indices were correlated to annual thermal, hydrologic, and global climate indices. Freshwater Drum expressed distinct and significant climate–growth relationships by water body type. The general pattern observed was that a...

A mathematical model was built and used to show the motion of particles in a cascade rotary drum dryer. In a cascade rotary drum the flights pick up the particles at a number of points in the lower half of the drum while, in the upper half, the particles fall freely. A model is derived where the drag force exerted on the particles throughout the falling period is emphasised. The motion of the particles in a rotary drum is described by three actions: Cascade; Kiln and Bouncing. In this study a horizontal rotary drum was used where both the kiln and bouncing actions have minimal effect, therefore, the focus is on the cascade motion of the particles. A characteristic of the model is the 'falling number' which is found to be dependent on the curtain properties. The model has demonstrated its ability to predict the effect of many important parameters such as drying medium velocity, drum rotation speed, particle size and feeding flow rate. It has been shown that increasing the drying medium velocity by 2.5 times results in an 85% decrease in the residence time. Also, the number of falling is shown to be limited and a function of the drum rotation speed, in this case 0.59 falling per second. An important feature of this model is the ability to predict the mean resident time, contact time interval and the resting time interval. The maximum error between the predicted and the measured data was

This paper is about designs placed on house-boards, shields and drums in the Min cultural sphere of Papua New Guinea. It is argued that the shields and drums can be understood as extensions of the Taro Mother ritual house built in the last of seven male initiation rituals performed in the area. The drum grows taro like the ritual house grows men, the shield attracts ancestral support to warriors like the facade of the ritual house attracts ancestral benevolence to the novices inside. In order to accomplish this the objects, and importantly their designs, are imbued with qualities considered agreeable to the ancestral spirits. It is suggested that as much as these qualities can be understood as part of the visual aspect of the designs, they are also, and importantly so, inherent in the substances used in their composition.

The mechanisms of segregation in solids mixing, even in simple rotating drums, are not clearly understood. Although most past studies have focused on binary mixtures, this work investigates the effect of polydispersity on granular flow, mixing, and segregation in a rotating drum operated in rolling regime through particle trajectories obtained from the radioactive particle tracking technique. Velocity profiles, radial segregation, and axial dispersion coefficients for monodisperse and polydisperse systems of glass beads are analyzed with respect to rotational speed and particle size. A model is introduced to predict the residence times along streamlines and evaluate the rate at which the material renews at the free surface and within the inner layers of the bed. Our results reveal similar velocity profiles and residence times for monodisperse and polydisperse systems. They also indicate that the particles distribute along the radial direction of the drum, although not necessarily in a core/shell configuration. © 2012 American Institute of Chemical Engineers AIChE J, 59: 1894–1905, 2013

Mining, construction and special vehicles for mass use are designed to work under high performances and offroad working conditions. Driving and executive mechanisms of support structures and superstructures of these vehicles operate frequently under high loads. These high loads, where the state of equipment is close to an incident, can jeopardize the dynamic stability of a machine. The experimental investigation is conducted on a Refuse Collection Vehicle (RCV). The aim of the research is to determine the real vehicle working conditions: Kinematics of the waste container (Hydraulic Rotate Drum for waste collection - HRD), dynamics of the load manipulator (superstructure), vibrations of the vehicle masses as well as strains (stresses) of the elements responsible for the supporting structure. Within the examination of the force (weight) on the rear axle of heavy vehicles, caused by their own weight and additional load, a universal measuring system is put forward. The results of this investigation present a p roposal of alternative system for continuous vehicle weighing that is characteristic for waste collection in motion (so-called On-Board Weighing System) and provide suggestions for measuring equipment designers .

The South Carolina Department of Natural Resources has been stocking red drum Sciaenops ocellatus since 1988 to evaluate parameters critical to their successful survival and recruitment in South Carolina estuaries. From 1999 to 2002, between 600,000 and 1,000,000 juvenile red drum were stocked each year in two tributaries of Charleston Harbor. The harbor and each tributary were partitioned into three independent strata and randomly sampled monthly for two decades, allowing population trends before, during, and after stocking to be evaluated. Using microsatellite-based parentage analysis, we examined the contribution of stocked age-0 juvenile red drum (15–60 mm total length) to the local population 1 year after release by using fishery-independent sampling. Analysis of these data showed that the highest contributions (88.9%) were close to the stocking site in years with low natural recruitment, whereas in years with high natural recruitment, contributions were lower and stocking was less effective...

In the pharmaceutical industry, more than half of all tablets receive a film coating. A commonly used technique is drum coating, where a film solution is applied to the moving tablets by a spray nozzle. Important process parameters include the amount and temperature of drying air, as well as spray nozzle position. Among other influences, the proper adjustment of these parameters has a great impact on spray loss, defined as the fraction of spray liquid that does not form a film on the tablets. Often, the lack of scientific data hinders a process setup based on engineering principles, resulting in operational conditions based on trial-and-error approaches. Here, we show how a coating system can be numerically modeled by means of computational fluid dynamics (CFD) techniques. Furthermore, we present how different parameters affect the efficiency of the process, leading to a deeper understanding of the coating device. © 2011 American Institute of Chemical Engineers AIChE J, 2012

Rotating drums are widely used in pharmaceutical industry to coat tablets. The motion of the tablet particle is one of the most important factors affecting coating uniformity. The purpose of the research is to experimentally investigate two important time variables for the coating process, residence time and turnover time, and their dependence on operating parameters (rotation speed and filling degree of the drum). The average residence time was found to decrease with increasing rotation speed and filling degree. The average turnover time was observed to increase approximately linearly with the inverse of the drum speed, but was found to be independent of the filling degree. A dimensionless time variable, the fractional residence time, i.e., the residence time divided by the turnover time, was introduced. Analysis showed that the fractional residence time could be a good indicator of coating uniformity. Results of the present work provide useful information for theoretical modeling which may ultimately serve as a tool for coating optimization.

Three-dimensional particle size segregation structures of binary mixtures of six different size ratios (SR = 1.42–3.37) in a rotating drum are studied. The formation of two smaller particle satellites around the central smaller-particle rich band after the band formation core-thickening mechanism is reported for the first time. The binary mixtures of six SRs show three satellite shapes, including the small bump shape, the axe shape, and the hemisphere shape. Except for the binary mixture of SR = 2.01 with the axe satellite shape, the satellite size increases with the increasing of the SR value at the same bed depth. The degrees of mixing of binary mixtures of six different SRs at different bed depths are analyzed using the Lacey mixing index. The degree of mixing at the bed surface and close to the drum cylindrical wall can be explained by the drift-diffusional model of Savage (1993). © 2011 American Institute of Chemical Engineers AIChE J, 2012

Grading potatoes by size is an important operation for preparing tubers for seed and for commercial purposes. Farmers in Iran and in developing countries grade potatoes by hand, which is very slow and costly. This work concerns the development of a potato-grading machine for small-scale farmers. The design is characterized by a spiral structure covered with a capron net to form a cribriform rotating drum as the grading surface. Potato tubers are fed into the drum, moved forward by the spiral structure, and dropped through holes of the net according to their dimensions. The design parameters included net stiffness (T), rotating drum speed (n) and feeding rate (q). The grading accuracy of the machine was evaluated to determine optimum condition of machine performance. An acceptable grading accuracy of about 70% with a low tuber damage of 5.5% were obtained at T = 0.14 N/mm, n = 27 rpm and q = 2,500 kg/h as optimum condition. PRACTICAL APPLICATIONS Commercial potato-grading machines are designed for medium- to large-scale farms, and are not suitable for the majority of farmers in developing countries. In these countries, grading of potato tubers, especially for seed purpose, is performed by hand, which is very time-consuming and labor-intensive. A small grading machine has been developed that can sort five times more tubers per person per unit time than the rate achieved by hand grading. The machine is very simply constructed and costs approximately US$800, which is considerably cheaper than current commercial grading machinery.

The present work analyzed aspects of the fluid dynamics of the conventional concurrent dryer equipped with lifting flights and their influence on the performance of a rotary dryer. The drying of granulated fertilizers (GTSP) in a conventional concurrent rotary dryer was experimentally investigated and compared with a modified configuration known as the roto-aerated dryer. The main feature of this new dryer is the presence of an aerated system consisting of a central pipe (encased in the drum) from which a series of mini-pipes lead hot air directly to the particle bed, flowing at the bottom (without flights). The results obtained confirm the superior performance of the roto-aerated dryer due to its more effective gas-particle contact.

Flutes are longitudinal grooves sculptured on the perimeter of the columns of ancient Greek or Roman temples. It is widely accepted that flutes were sculptured mainly for aesthetic reasons. However, strong indications exist that the presence of flutes somehow changes the overall mechanical behaviour of the column. This could be expected due to the singularities introduced by the imposed abrupt change in the boundary conditions of the specimen, where the friction boundary of the base meets the free boundary of the lateral surface. Following the previous line of thought it was decided to check this hypothesis by studying the mechanical behaviour of a typical drum of a column of the Parthenon Temple of the Acropolis of Athens. These columns have 20 flutes and their shape is accurately described as an arc of an ellipse. The study was carried out both numerically and experimentally. The parameters studied included the number and the shape of the flutes as well as the type of loading. It was concluded that the presence of flutes significantly modifies the stress and strain fields developed especially under torsion. In addition, the fluted drum appeared to be stiffer in comparison with the non-fluted one.

Hybridization, development, juvenile growth in ponds, and morphological characteristics of black drum (Pogonias cromis) female x red drum (Sciaenops ocellatus) male hybrids are described. Hormone (HCG) injection was used to induce ovulation in a field collected black drum. Spermatogenesis was induced in a laboratory maintained red drum by temperature and photoperiod manipulation. Hybridization was accomplished by strip-spawning with a fertilization rate of 66%. Hatching began 30 hours post-fertilization at 21–22°C, and mean total length of newly hatched fry was 1.6 mm. Mouthpart development was complete 58 hours post-hatch, at which time larval fish were stocked into a 0.8 hectare fertilized pond. After 34 days, mean total length was 33.1 mm and survival was 16.6%. Approximately 13,000 hybrids were retained, fed commercial salmon feed, and harvested after 197 days. Mean total length at harvest was 189 mm. Mean daily growth rate was 0.81 mm/day while the food conversion efficiency was 1.9. Hybrid pigmentation patterns, number of anal rays, and the number of gill rakers were intermediate between the parent species.