Size Of Pieces Research Articles

A model to predict productivity of different chipping operations

The chipping operation is an important component of harvesting systems producing biomass and pulp chips. This paper aimed to develop a valid model to predict the productivity of chipping as part of these operations. Over a number of years more than 200 different time studies were conducted on chipping operations in Italy and Australia. Multiple regressions and backward stepwise data analysis methods were applied to develop a productivity prediction equation, considering the following variables: machine power (kW), piece size (m3), crew size, harvesting method, species, tree part, wood condition, wood lay-out, chipping type, propulsion, feeding method, point of chipping, season, location of chip discharge, country (Italy or Australia) and type of operation (biomass chip operation or pulp chip operation). The final productivity model included machine power, average piece size, location of chip discharge and type of operation as significant variables. The internal validation test was conducted using five witness samples from Italy and Australia, which confirmed the validity at α=0.05. Additional international case studies from North America, South America, and central and northern Europe were used to test the accuracy of the model, in which 15 studies confirmed the model's validity and two failed to pass the test.

Impact of fruit piece structure in yogurts on the dynamics of aroma release and sensory perception.

The aim of this work was to gain insight into the effect of food formulation on aroma release and perception, both of which playing an important role in food appreciation. The quality and quantity of retronasal aroma released during food consumption affect the exposure time of olfactory receptors to aroma stimuli, which can influence nutritional and hedonic characteristics, as well as consumption behaviors. In yogurts, fruit preparation formulation can be a key factor to modulate aroma stimulation. In this context, the impact of size and hardness of fruit pieces in fat-free pear yogurts was studied. Proton Transfer Reaction-Mass Spectrometry (PTR-MS) was used to allow sensitive and on-line monitoring of volatile odorous compound release in the breath during consumption. In parallel, a trained panel used sensory profile and Temporal Dominance of Sensations (TDS) methods to characterize yogurt sensory properties and their dynamic changes during consumption. Results showed that the size of pear pieces had few effects on aroma release and perception of yogurts, whereas fruit hardness significantly influenced them. Despite the fact that yogurts presented short and similar residence times in the mouth, this study showed that fruit preparation could be an interesting formulation factor to enhance exposure time to stimuli and thus modify food consumption behaviors. These results could be taken into account to formulate new products that integrate both nutritional and sensory criteria.

Metal ion-directed solution-phase tailoring: from large-area graphene oxide into nanoscale pieces.

Due to fascinating electronic properties and great potential in various applications, graphene has attracted great interest. Recently, much work have focused on the synthesis of different sizes and properties of graphene or graphene oxides (GOs), for example, graphene nanoribbons, nanosized graphene pieces, and nanosized triangular and hexagonal graphene sheets terminated by zigzag edges. Herein, we have demonstrated a widely available approach to fabricate the nanoscale GO pieces by directly solution-phase cutting a large-area GO sheet into nanoscale pieces via spontaneous redox reactions at room temperature. In this process, GO acts with dual functions as a model and a reducing reagent. With a typical example of silver ions, we have investigated in detail the influence of the reaction time and concentration of metal ions on yield and size of nanoscale GO pieces. Moreover, we also obtain Ag nanoparticle coating on the GO surface. Finally, a possible mechanism is suggested to explain the formation of nanoscale GO pieces.

Influence of the Type of Strain Measurement Device and of the Speed of Loading and Unloading of the Testing Machine in the Determination of the Static Modulus of Elasticity of the Concrete

This paper presents a comparative analysis of the results obtained for testing the tensile modulus, through a collaborative program of tests on hardened concrete, developed at the School of Civil Engineering, Federal University of Goias, in the Department of Technical Support and Control of Furnas central Electric Company SA and Carlos Campos and Construction Consultancy Limited., to identify and assess the influence of some factors involved in the test results the elastic modulus. This test was performed according to ABNT NBR 8522:2008, loading plan initial tangent modulus characterizing the deformation of concrete subjected to the stresses of 0.5 MPa and 30% of the breaking load. For this, we sought to determine the outcome of the module, the influence of strain gauge (compressometro mechanical, electrical bonding surface extensometer extensometer and electric external fixation) and rate (0.3 and 0.6 MPa/s) bodies on the test piece cylindrical size 150 mm x 300 mm C30 concrete class. We performed 60 trials considering the results with satisfactory performance in the statistical techniques of the program. It was concluded that the strain gauge type of load and speed significantly influenced the results of elastic modulus. Moreover, it is noteworthy that the bodies of the test piece size 150 mm x 300 mm concrete Class C30, tested with loading speed of the testing machine of 0.3 MPa/s presented the results with the highest dispersion. Keyword: Meter, Speed; Module; Concrete; Dispersion.

Effect of piece size and tree part on chipper performance

A commercial drum chipper was fed alternately and piecewise with poplar stems and poplar tops, in order to determine the effect of piece size and tree part on machine performance. Chipping stems required most of the available power (231 kW) delivered by the tractor, whereas chipping tops took about half that much. However, productivity was twice as high with stems, compared to tops (i.e. 25 and 11 t h−1 of oven dry wood, respectively). As a consequence, specific fuel consumption per unit product was 15% lower with stems, compared to tops – i.e. 0.61 and 0.72 L m−3, respectively. Mean feeding speed was 0.37 m s−1 for stems and 0.41 m s−1 for tops, but the difference was not significant (p = 0.1677). Productivity and fuel consumption were strongly related to piece size, but tree part had its own additional effect, independent from size and possibly related to form. When chipping tops it is advisable to feed more pieces at a time, in order to partly compensate for the effect of piece size. Operators expecting to chip primarily small-size materials may acquire special chipper versions with wider drums and additional side rollers, for smoother mass feeding.

Organic carbon export in the form of wood during an extreme tropical storm, Upper Rio Chagres, Panama

ABSTRACTWidespread, intense rainfall over the Upper Rio Chagres watershed (414 km2) in central Panama during December 2010 triggered numerous landslides that introduced large numbers of trees to the river network. We flew by helicopter along the mainstem Upper Chagres and the adjacent margins of Lake Alhajuela, into which the Upper Chagres flows, in February and June 2011. We used low‐elevation video photography from these flights to tally the number of wood pieces stored along the lake margin and within the channel, and the number of landslides reaching the mainstem. We used these tallies with ground‐verified estimates of average wood piece size and landslide surface area, and assumptions about wood density, carbon content, and aboveground biomass, to develop a first‐order estimate of carbon export in the form of wood from the Upper Chagres following the 2010 storms. Based on the wood tally, we estimate 9 · 6 to 16 Mg C/km2export, and from the landslide tally we estimate 24 Mg C/km2. We believe the landslide tally provides a more accurate minimum estimate of carbon export from the Upper Chagres during the December 2010 storms. These values are an order of magnitude higher than limited data for average or background rates of wood‐based carbon export from other catchments, but two orders of magnitude lower than wood‐based carbon export during extreme storms in Taiwan. The findings suggest that duration of flood flow above a threshold for mobilizing wood within the channel network exerts a more important control on wood export from the Upper Chagres than magnitude of flood peak. Copyright © 2013 John Wiley & Sons, Ltd.

Katol Meteorite Shower, Maharashtra: A Preliminary Study

Abstract: A meteorite shower occurred in Katol (21° 15' 30" N ; 78° 35' 00" E ; at an elevation of 415 m above msl), Nagpur district of Maharashtra state, India on May 22, 2012 between 14:00 to 14:30 hrs (Indian Standard Time) with a presently observed strewn field of ~5.0 sq km area. The event was experienced by the hundreds of inhabitants with a loud noise and fire ball between Akola in the west to Nagpur in the east. The Geological Survey of India has so far collected 27 meteorite pieces with a total weight of 3500 gm. The locations, size, shape and surface features of the individual meteorite pieces have been recorded. Based on their physical properties, mineralogy, mineral chemical mapping and REE chemistry, the Katol meteorites have been classified as olivine-rich H5 type differentiated stony meteorite with reconstituted chondrules. The preliminary evidence suggests the presence of pre-solar grains in Katol meteorite.

Contribution to the Experimental Study of the Concrete Behavior in Its Climatic Environment

Several studies have demonstrated the aggressive effect of very high temperatures, exceeding 100°C, on the behavior of concrete. However, the effect of local service temperatures remains significant, even very important, if we consider the safety margins provided during the sizing of pieces in the warm regions and their severe climatic conditions of the setting and hardening. In this context, the data on the behavior of the concretes at service temperatures are necessary to predict the safety of the buildings and constructions in various regions. The main objective of this paper is to determine the sensibility of the concrete to its climatic environment, during the period of service in the Saharan regions. It has been shown, by using three different compositions of concrete based on local materials, that the performance of concrete fall considerably with the increase of the temperature until 60°C. A thermal enclosure was conceived; the evolutions of the strength are presented and compared with those obtained for the reference results at 20°C temperature. The consequences on the durability and the reliability of structures in these regions are important, which appeals to the necessity in a consideration the risks caused by geo-climatic conditions during the design of structures.

Comparing the efficiency of drum and disc chippers

The study compared the effect of chipper type on productivity, power demand, fuel consumption and product quality. Tests were conducted on two commercial chipper models, a disc and a drum chipper. Both chippers had the same diameter capacity, were applied to the same tractor and fed with the same feedstock types. Fifteen replications were conducted per machine and for each of four different feedstock types, reaching a total of 120 tests. The disc chipper had a higher energy efficiency and used 19% less fuel per unit product, possibly due to its simpler design, integrating comminuting and discharge system in one synergic device. In contrast, the drum chipper was 8% more productive, since it cut with the same energy all along the length of its knives. The drum chipper produced smaller chips, with a higher incidence of fines. Feedstock type had a strong effect on productivity, energy efficiency and product quality. The effect of feedstock type was mainly related to piece size, and may be stronger than the effect of chipper type. Further studies should determine the effect of blade wear on the relative performance of the two chipper types.

An Analysis Model for Structural Optimization of Polygon Ranging-Based Space Coordinate Measurement Network

Polygon ranging-based space coordinate measurement network, which has high measurement accuracy and simple structure, is suitable for large-scale metrology. In practice, the measurement network should be constructed flexibly according to coverage and shape and measurement accuracy of different measurand. Based on this, a universal analysis model of structural optimization is proposed. The relation between structural parameters (amount and layout of measurement base stations) and distribution of measurement accuracy of the measurement network are researched on the model. The model can provide theoretic basis for optimized and flexible design of the measurement network. A case is used to illustrate this model. The results verify that the module can be used for scientifically establishing measurement system of ultra-large size, and also preliminarily simulating and optimally designing the being adopted measurement network and measurement method for meeting requirements of size and measurement accuracy (including global and local accuracy) of different work pieces.

Analytical methods in assessing coke properties

Dynamic calculations of coke disintegration are considered. The change in mean piece size (geometric and harmonic means) corresponds to the coke quality. The relative ease of crushing (or erosion) shows how one coke compares to another. These characteristics provide improved ability to distinguish between batches of coke and are readily interpreted.

Robust Algorithms for Preemptive Scheduling

Preemptive scheduling problems on parallel machines are classic problems. Given the goal of minimizing the makespan, they are polynomially solvable even for the most general model of unrelated machines. In these problems, a set of jobs is to be assigned to run on a set of m machines. A job can be split into parts arbitrarily and these parts are to be assigned to time slots on the machines without parallelism, that is, for every job, at most one of its parts can be processed at each time. Motivated by sensitivity analysis and online algorithms, we investigate the problem of designing robust algorithms for constructing preemptive schedules. Robust algorithms receive one piece of input at a time. They may change a small portion of the solution as an additional part of the input is revealed. The capacity of change is based on the size of the new piece of input. For scheduling problems, the supremum ratio between the total size of the jobs (or parts of jobs) which may be re-scheduled upon the arrival of a new job j, and the size of j, is called migration factor. We design a strongly optimal algorithm with the migration factor $1-\frac{1}{m}$ for identical machines. Strongly optimal algorithms avoid idle time and create solutions where the (non-increasingly) sorted vector of completion times of the machines is lexicographically minimal. In the case of identical machines this results not only in makespan minimization, but the created solution is also optimal with respect to any l p norm (for p>1). We show that an algorithm of a smaller migration factor cannot be optimal with respect to makespan or any other l p norm, thus the result is best possible in this sense as well. We further show that neither uniformly related machines nor identical machines with restricted assignment admit an optimal algorithm with a constant migration factor. This lower bound holds both for makespan minimization and for any l p norm. Finally, we analyze the case of two machines and show that in this case it is still possible to maintain an optimal schedule with a small migration factor in the cases of two uniformly related machines and two identical machines with restricted assignment.

Micromachining of commodity plastics by proton beam writing and fabrication of spatial resolution test-chart for neutron radiography

Proton beam writing is a direct-write technique and a promising method for the micromachining of commodity plastics such as acrylic resins. Herein, we describe the fabrication of microscopic devices made from a relatively thick (∼75μm) acrylic sheet using proton beam writing. In addition, a software package that converts image pixels into coordinates data was developed, and the successful fabrication of a very fine jigsaw puzzle was achieved. The size of the jigsaw puzzle pieces was 50×50μm. For practical use, a prototype of a line and space test-chart was also successfully fabricated for the determination of spatial resolution in neutron radiography.

Determining the shape of the productivity function for mechanized felling and felling-processing

Productivity studies in forest operations are often carried out on new equipment, or on equipment being used in new conditions. Understanding how stand and terrain parameters impact the productivity of harvesting machines is important for determining their optimum use. Such information is normally presented as a productivity or efficiency function; that is, a regression equation that best represents the data. Most studies establish that piece size is the dominant predictor that impacts overall productivity. A common concept known as the “piece-size law” is that productivity increases at a decreasing rate with increasing piece size. What is not well understood is the upper limit to this piece-size law. That is, as the trees get “too” large, we can expect the machine to start to struggle, resulting in a decrease in productivity. Four different data sets—two based in New Zealand and two in Italy—are presented that clearly show an “optimum” piece size for maximum productivity. On average, productivity tended to decrease gradually, not drop off suddenly beyond the optimum. Using more complex statistical functions, it was possible to correctly correlate piece size to productivity.

Interference measurements in nanotechnologies

Many modern technologies for the production of nanomaterials require an operational diagnostic with a high defect detection capability for the products immediately during the production process. These technologies include, in particular, plasma nanotechnologies for the creation of nanostructures and coatings, electron-beam epitaxy technologies, new deposition technologies for films and coatings, bulk and surface nanostructuring of metallic materials, technologies for making multilayer dislocation-free silicon nanostructures for electronic devices; technologies for fabricating optical mirrors based on nanostructured powders of silicon and its chemical compounds; roll technologies for fabrication of diffraction elements and solar cell matrices, nanostructured substrates for nano- and microelectronics. The distinctive features of these technologies are their high productivity, the different sizes of the work pieces, strict specifications on the topological characteristics of surface shapes and textures, and the thicknesses and optical characteristics of films and coatings. During execution of most of these technologies, primary attention is devoted to the search for and analysis of defects whose dimensions are much smaller than an optical wavelength. These measurements are needed both in final production and in engineering setup, i.e., the nanostructured substrates on which the work pieces are formed, the master matrices used in rolling technologies, etc. An analysis of technologies of this kind makes it possible to formulate specifications for the measurement and diagnostic equipment used in these technologies: contactless measurements, high productivity, in situ measurements, the ability to detect defects of nanometer size. Optical methods are generally used for this kind of measurements in production lines, e.g., interferometry, including holographic and speckle interferometry, ellipsometry, confocal and scanning microscopy, all with a high operational measurement capacity and noninvasive. Improvements in these methods have led to some surprising results. Modern optical systems make it possible to measure deviations in the shape and structure of surfaces with an error of 0.1‐0.2 nm, determine a lateral change in an object by 3‐5 nm, and measure the thicknesses of multilayer coatings with an accuracy of 1‐2 nm [1, 2]. These systems must be capable of measuring 5‐10 wafers per hour for diagnostics of 1‐2 gigapixel work pieces. All the above remarks are confirmed by the need to develop apparatus and methods in the nanoindustry with modern instrumentation for contactless operational monitoring of surface nanorelief and texture in the manufactured products. The use of optical measurement techniques presupposes, first of all, the establishment of a relationship between the parameters of the detected light and the properties of a material, second, the use of optical devices for measuring the parameters of the light, and, third, recovery of the properties of the material from the measured parameters of the light.

Effect of cross wedge rolling on the microstructure of GH4169 alloy

The metal microstructure during the hot forming process has a significant effect on the mechanical properties of final products. To study the microstructural evolution of the cross wedge rolling (CWR) process, the microstructural model of GH4169 alloy was programmed into the user subroutine of DEFORM-3D by FORTRAN. Then, a coupled thermo-mechanical and microstructural simulation was performed under different conditions of CWR, such as area reduction, rolling temperature, and roll speed. Comparing experimental data with simulation results, the difference in average grain size is from 11.2% to 33.4% so it is verified that the microstructural model of GH4169 alloy is reliable and accurate. The fine grain of about 12–15 μm could be obtained by the CWR process, and the grain distribution is very homogeneous. For the symmetry plane, increasing the area reduction is helpful to refine the grain and the value should be around 61%. Moreover, when the rolling temperature changes from 1000 to 1100°C and the roll speed from 6 to 10 r·min−1, the grain size of the rolled piece decreases first and then increases. The temperature may be better to choose the value around 1050°C and the speed less than 10 r·min−1.

Deadwood specific density and its influential factors: A case study from a pure Norway spruce old-growth forest in the Eastern Carpathians

Deadwood is a pivotal component of old-growth forests that plays an important role in both carbon sequestration and cycling. Deadwood carbon estimates rely on the conversion of easily measured volumes into dry masses, using decay-class conversion factors. Little is known about the specific dry density of deadwood in Norway spruce (Picea abies (L.) Karst) old-growth forests, especially in temperate mountainous zones. We studied specific density variations of standing and lying deadwood in an old-growth forest from the Central Eastern Carpathians. Using a balanced sampling, the piece size, rottenness percent (proportion of rotten wood within a sample) and decay, ordered in a 2-class scale for snags and an 8-class scale for logs, were recorded. For logs, the position of the sampling along piece (top, middle, bottom) and the contact with the ground were considered as additional factors. The decay classification for logs was intentionally large, aiming to test for an optimal number of decay classes. The mean density showed small variations within snag classes (322.0kgm−3/319.7kgm−3), ranging between 342.7kgm−3 and 151.7kgm−3 for logs. The rottenness in snags was very even (40–43%), while it increased with the decay class for logs as expected. The mean mass moisture variation was larger than in other studies, between 38.5–268.6%, with the highest variation in the higher classes (5–8), while volumetric moisture varied between 11.6% and 39.7%. The samples from the base of the log positively influenced the moisture, while the contact had only marginal effects. The relationship between the dry density and the above factors was modeled using mixed-effect models. Apart from decay class, moisture and rottenness explained more variance than any other investigated factor (position, elevation, ground contact). The best model, which explained up to 76% of the total variance, included the rottenness percent and the decay class as fixed effects and the sample piece as a random effect. The overall best performing model on a four-class decay system had the same structure. We recommend using a decay system with fewer classes to effectively estimate specific deadwood dry density.

Hiperparatiroidismo primario y crisis hipercalcémica aguda tóxica

ObjectivesTo describe the clinical characteristics and surgical treatment of patients with acute hypercalcaemia due to primary hyperparathyroidism (PHPT) and compare them with other patients with PHPT without associated acute hypercalcaemia. Material and methodsA prospective, observational study (1998-2010) was conducted on 158 patients with PHPT treated by parathyroidectomy. Those with acute hypercalcaemia (>14mg/dl -3.5mmol/L- or >3mmol/L with symptoms of calcium toxicity) were evaluated by recording their clinical and treatment characteristics, and comparing them, using the Mann-Whitney U test and the Fisher test, with the 146 PHPT patients without hypercalcaemic crisis. ResultsTwelve patients (7.6%) had acute hypercalcaemia with symptoms of calcium toxicity and other symptoms of chronicity. The preoperative calcium and PTH values were 14.5±1.3mg/dL and 648.2±542pg/dL, respectively. There were 10 adenomas, 1 hyperplasia and 1 carcinoma. The mean weight of the surgical pieces was 4.075±2.918mg, with a diameter greater than 27±14mm. The gradients of PTH at 10 and 25minutes were 79±18% and 92±6%, respectively. Post-operative calcium values on discharge and at 6 months were 8.2±0.7mg/dL and 9.1±0.9mg/dL, respectively. The plasma concentrations of calcium, PTH, and the size of the surgical pieces were higher in patients with hypercalcaemic crisis (P<0.001). There were no differences in the other parameters studied or in the cure rate. ConclusionsHypercalcaemic crises were caused by larger and heavier tumours that led to higher plasma Ca and PTH plasma concentrations. All patients had long-standing symptoms and parathyroidectomy led to cure of the disease.

EFFICACY OF NOVEL SB KNIFE JR EXAMINED IN A MULTICENTER STUDY ON COLORECTAL ENDOSCOPIC SUBMUCOSAL DISSECTION

Secure manipulation of forceps in endoscopic submucosal dissection (ESD) for colorectal tumors is sometimes hindered by the characteristics of that organ. SB knife Jr, which are scissor forceps using a mono-pole high frequency, were developed to avoid the difficulty of ESD operation in the colorectum. The aim of the present study was to examine the effectiveness of the SB knife Jr in colorectal ESD in 11 hospitals, mostly in northeastern Japan. One hundred and two colorectal tumors (49 non-granular laterally spreading tumor [LST] lesions, 39 granular LST lesions and 14 other lesions) that were resected by ESD operations using SB knife Jr between October 2009 and March 2010. All tumors (102/102) were resected en bloc and could be observed in detail. The mean size of the resected pieces was 40.3 mm. The mean operation time was 54.2 min. Of the complications, one case of micro-perforation occurred during the manipulation of submucosal dissection, and this case was treated with clips in that operation. The rates of resection carried out only with SB knife Jr were 74.5% (76/102). The novel ESD using SB knife Jr in the colorectum offers a breakthrough in resection techniques for not only expert endoscopists but also general endoscopists.

Implementation and validation of video monitoring for wood budgeting in a wandering piedmont river, the Ain River (France)

ABSTRACTThe transport of wood in rivers during floods is an important process that underlies differences in habitat and morphology between water courses and regions. Quantitative data are needed to properly address management objectives and balance wood budgets. In this study we use a streamside video camera to detect wood passage and measure quasi‐instantaneous rates of wood transport in the Ain River, France. The objectives are to verify the procedure, describe the relation between wood transport and discharge, and construct and validate a wood budget for the reach upstream of the camera. Verification of the procedure includes tests of detection frequency, wood velocity, and piece size. A log base two transformation is proposed to classify wood by piece length. It was found that a wood transport threshold occurs at approximately two thirds of the bankfull discharge. Wood transport follows a positive linear relation with discharge up to the bankfull discharge but is both more variable and less sensitive to discharge when the floodplain is inundated. Transport rates are approximately four times higher on the rising limb of the hydrograph than on the falling limb. Wood transport estimates from a three‐stage rating curve are two to 10 times higher than those from a wood budget using local and aerial surveys of upstream dynamics. Future work should address uncertainties related to wood diameter measurements, sampling length and frequency, and antecedent floods. Copyright © 2012 John Wiley &amp; Sons, Ltd.