دانلود گزارش کارورزی و کار آموزی

چکیده : 

We extend prior research on the value relevance of accounting information for lossmaking

firms by allowing the coefficient of book value to vary across three distinct set

of loss-making firm observations in our valuation model. Our key findings are, first, that

book value is a less important determinant of equity value for either high R&D-intensive

firms or dividend-paying firms, relative to firms with low R&D-intensity and zero dividends.

Prior literature suggests that book value is a strong indicator of firm value for lossmaking

firms. This reasoning stems from book value’s role as: (i) a proxy for the value of

the possibility of abandoning or adapting the firms’ net assets; and/or (ii) a proxy for

expected future normal earnings. Our work suggests that this prior literature does not fully

capture the valuation role of book value for loss-making firms. Second, we also find that

dividends are value relevant, but generally only when the valuation role of book value is

contextualised by allowing its coefficient to vary across high R&D-intensive firms, and

dividend-paying, loss-making firms

چکیده : 

The flow characteristics of a powder system are known to be influenced by particle size distribution, particularly

the content of fine particles, and interparticle forces. This paper reports an investigation that has

identified and quantified links between physical properties, viz size distribution, bulk density and particle

density, and cohesion in compacted beds of powder. An annular shear cell was used in the determination

of the cohesion of cohesive and free-flowing milled lactose powders at low consolidation stresses in the

range 0.31–4.85 kPa and under ambient conditions. Following consideration of the compaction and

shearing processes, it was postulated and confirmed that cohesion could be expressed as a function of

powder surface area per unit volume and dimensionless preconsolidation stress. It was shown that care

is needed in the measurement of surface–volume mean diameter when applying correlations developed

from the experimental data.

چکیده : 

Discrete Element Method computer simulations have been carried out to analyse the influence of the

hydrophobic force model on the capture of particles by a central bubble. Two hundred particles, with

diameters ranging between 24 and 66 lm, were randomly positioned within a maximum distance from

the surface of a bubble of 2 mm in diameter. Initial particle velocities were random in direction and value

and they followed Gaussian distributions with standard deviations between 0.0 and 1.0 m/s. Three possible

models, named A, B and C have been used in the simulations. The models correspond to different

published relationships of the hydrophobic force with the distance between particle and bubble surfaces,

d. Model A corresponds to a hydrophobic force that decays in the form 1/d; the hydrophobic force given

by Model B uses a relationship in the form 1/d2; Model C predicts a force that decays in an exponential

way in the form exp(d/k). These models have also been compared with a base case in which the hydrophobic

force only acted when the particles were in contact with the bubble. Therefore, we could better

discern between the influence of the initial particle velocities and the long range component of the

hydrophobic force. The differences in the capture efficiency of the particles predicted by the three models

were drastic. All particles were captured by the bubble in the cases simulated using Model A for any particle–

bubble surface distance smaller than 1 mm. However, only 40% and 60% of the particles were captured

even for particles located at distances of less than 50 lm from the bubble surface in the cases

simulated using Models B and C ( lm), respectively. In fact, the capture of particles seems to be more

strongly influenced by how the hydrophobic force decays with interparticle distance in the range of tens

of micrometres rather than by the differences between the models in the range of micrometres. Therefore,

this work should aid in the future determination of a general hydrophobic force model through

an experimental comparison of the kinetics of collision of particles against bubbles in flotation cells with

the simulation results

چکیده : 

One method to reduce the energy consumption of industrial milk spray dryers is to recover waste heat

from the exhaust dryer air. A significant challenge associated with this opportunity is the air contains

a small amount of powder that may deposit on the face and surfaces of a recuperator. This paper introduces

a novel lab based test that simulates powder deposition on a bank of parallel plate fins at exhaust

dryer air conditions. The fin bank acts like the face of a typical finned tube row in a recuperator. The aim

of this study is to look at how deposition on the front of fins is affected by the air conditions. Results show

similar characteristics to other milk powder deposition studies that exhibit a dramatic increase in deposition

once critical stickiness levels are reached. As powder deposits on the face of the fins, the pressure

drop across the bank increases until eventually an asymptote occurs, at which point the rates of deposition

and removal are similar. For very sticky conditions, deposition on the face of the fins can cause a rise

in the pressure drop by as much as 65%. The pressure drop has also been successfully related to the percentage

of open frontal area of the fins with and without deposition. Deposition inside and at the rear of

the fin bank was found to be minimal.

چکیده : 

Mesoporous carbons were synthesized by organic–organic self-assembly of triblock copolymer F127 and

phenolic resin oligomers composed of resorcinol–formaldehyde or resorcinol–furfural. The mesostructure

control was performed by using different polymerization catalysts, ammonia and acetic acid. The

effects of the aldehyde and polymerization catalyst on pore architecture of mesoporous carbons were

investigated. Disordered mesostructure with poorly disconnected mesopores was formed using furfural.

In contrast, when formaldehyde was used, ordered structure with mesochannels was formed. In addition,

changes in mesochannel length and the degree of long-range order are found to depend on polymerization

catalyst. The porous carbons with different structure were used as a model material to investigate

the ion storage/transfer behavior in electrical double-layer capacitor. Electrochemical cyclic voltammetry

measurements were conducted in 1 Msulfuric acid electrolyte solution. The ordered mesoporous carbons

show superior capacitances and rate performance over the disordered carbons. Electrochemical impedance

spectroscopy was used to assess the transport properties. The impedance data clearly demonstrated

that the degree of long-range order and channel length can influence the ion transport, resulting in superior

capacitive performances.

چکیده : 

The dynamics of a powder flowing in a mass flow regime through a storage bin with a conical hopper, is a

well studied problem. However, many challenges remain, including quantification of the mixing that

occurs during discharge through the hopper. We have formulated a model based on the conservation

of volume of the powder and a semi-empirical expression for velocity profile, (see [1,2]), and used this

to estimate mixing parameters. We have specifically considered the case of an inflow which is disposed

in homogeneous horizontal layers as it enters the storage bin. When the powder, in successive layers,

enters the hopper, it accelerates and its velocity along the longitudinal axis of the hopper is greater than

at the walls. Portions of layers high in the hopper may overtake layers closer to the exit resulting in mixing

of the layers. Using this model we are able to quantify the percentage of each layer in a given output

volume and present results for typical hopper geometries.

چکیده : 

A newly developed mechanochemical process for the simple aqueous phase synthesis of crystalline magnetite

nanoparticles has been experimentally investigated. In this process, a suspension of ferric hydroxide

precursor is milled at room temperature using a horizontal tumbling ball mill consisting of a stainless

steel pot and balls. Ferric hydroxide is transformed to magnetite without the use of a reducing agent. As a

model starting material for the investigation, a pH-adjusted suspension of crystalline goethite was used.

As the milling time increased, goethite disappeared along with the simultaneous formation of magnetite.

A single phase of magnetite was obtained after 16 h of milling. A reaction mechanism for the formation of

magnetite has been proposed based on oxidation–reduction reactions, in which the corrosion of iron in

the pot and balls plays an important role. Free electrons are generated by the release of ferrous ions from

the stainless steel in an anodic reaction, which then reduce goethite to ferrous hydroxide in a cathodic

reaction. The solid phase reaction between ferrous hydroxide and goethite produces magnetite. Not only

could the mechanochemical effect induced by the collision of balls accelerate the corrosion even under

alkaline conditions, it can also promote the formation and crystallization of magnetite.

چکیده : 

A novel method for directly measuring the temperature history of mobile hot ferromagnetic particles

(steel particles), substituting for reacting particles, in a binary-solid (reacting particles and inert particles)

downflow is introduced. The temperature history of the hot steel particles can be obtained by measuring

the temperature of the particles at different axial positions using magnetic fields that can separate the

steel particles from other bed materials immediately and easily. Employing the magnetic marking

method, magnetic sensors were used to detect the change in magnetic flux density in a given magnetic

field, and the residence time of the steel particles was also measured. The cross-sectional averaged particle-

to-bed heat transfer coefficients were calculated from the experimental results using simple heat

balance equations. The measured temperature data have a relatively wide error range; however, the average

temperature curves derived from the average particle-to-bed heat transfer coefficients agreed with

the temperature plots. Therefore, the experimental method of this study is applicable to the measurement

of the particle temperature in a binary-solid downflow. The results showed that there is strong correlation

between the particle-to-bed heat transfer coefficients and normalized collision frequency under

the laminar gas flow conditions

چکیده :