The development of a simulation strategy and modelling algorithm with potential application to a variety of food process operations, particularly to thermal processing of canned foodstuffs has been undertaken. A review of published work identified previous efforts in the development of mathematical models for thennal process operations, including their limitations. The review showed that Finite Difference methods have found wide application in modelling conduction heating of canned foods. A similar model would be a useful numerical yardstick for validating any developments in this work. The great diversity of food handling operations have been grouped into a more manageable small number of classes. Such classification recognised that sets of related operations share common characteristics and functions which are the basis for the development of mathematical models for each class of operations. The strategy developed involved hierarchical decomposition of unit operations into assemblies of basic modules and mathematical modelling of these basics. A model of the operation can then be constructed simply by selecting and arranging the required basic units with due consideration to the boundary conditions of the physical problem. For transient operations with positional variation, these elementary modules have been termed "zones". The range of basic zones to model representative units have been identified. This hierarchical zone-model simulation has been demonstrated for heat transfer in a cylindrical container and for batch retort operation. The repeated use of the same unit modules for different operations makes this a flexible and robust strategy. The mathematics of zone-modelling has been developed for heat conduction in foodstuffs in cylindrical containers. To ensure accuracy, the numerical integration steps were rigorously monitored using mathematical procedures well-established for this purpose. The validity of the model has been tested against the analytical and implicit finite difference solutions. Generally, zone models agreed within 1 % of these standard yardsticks with the difference becoming negligible when sufficiently small integration steps or zone sizes were used. The effectiveness of zone-modelling as a simulation tool has been established using experimental data and the various sources of discrepancy between the model and experimental data accounted for. Thermocouple measurement errors have been found to have contributed most significantly to this discrepancy. Detailed analysis and modelling of thermocouple measurement errors has been carried out using zone-modelling to simulate the true experimental system which accounted for the presence of a thermocouple. The result has been an improved agreement between experiment and the zonemodel, and it also demonstrated the flexibility of the modelling technique. Further resuhs have shown that the discrepancy varied with thermocouple size and type. The contributions to error of temperature variability of, and of uncertainty in, thermophysical properties of the food were discussed. , The flexibility and robustness of zone-modelling have been further demonstrated using some practical situations including heat transfer to foodstuff in flexible packaging - such as sausage rolls, heat transfer in a food container with varying headspaces and the consequence of steam interruption during processing. Examples have been discussed of other transient processes that could similarly be modelled using this technique. The main achievements of this work include the application of hierarchical simulation and zonemodelling techniques to food processing and the development of a novel mathematical modelling technique which is more flexible than finite differences. Moreover, the applications of zonemodelling to the study of thermocouple errors, to the study of the consequences of steam interruption during thermal processing, and to heat transfer in foods in flexible containers, are developments of interest in food processing. It is concluded that the hierarchical simulation and zone modelling algorithm are robust and flexible techniques with potential applications in food process simulation .

Accuracy of fatigue life prediction of solder joint materials using the finite element method (FEM) depends on realistic and reliable constitutive models and the FEM procedure itself. The effectiveness and accuracy of a constitutive model to simulate and predict the behavior of materials strongly depends on consistent, reliable and precise experimental data. In this research, a thermomechanical digital image correlation test device has been developed to investigate solder joint material behavior under thermal mechanical and cyclic loading. The test device is composed of two high precision actuators driven by two brushless servo-motors; a vacuum chamber used to prevent the heating and cooling plate from heating and cooling the air in the vacuum chamber and other components to save the energy needed to heat and cool the specimen; a heating and cooling unit composed of four Peltier devices; a digital correlation deformation and displacement measurement system and various load and displacement sensors. The test device is controlled by Labview. Two closed loop system control programs in Labview were developed to control the device and perform tests under specified loads, displacements and temperature profiles. The temperature, loads, and displacements can be applied manually and automatically. A series of tests such as normal load tests, temperature and rate dependent tests, isothermal mechanical fatigue and thermomechanical fatigue tests have been carried out on 63Sn/37Pb and 60Sn/40Pb solder joint materials. The rate and temperature dependent test results are consistent, which shows that newly developed test device is reliable. Material parameters for the HISS and DSC models were computed from the test data, which can be used to investigate the failure mechanism of solder joints in electronic packaging to improve the reliability of electronic packaging. Disturbed State Concept (DSC) constitutive model is a powerful tool for the simulation and prediction of material damage, failure and fatigue. Strain localization and material softening cause negative-semi definite finite element stiffness-matrix, which create numerical difficulties for the calculation of DSC. A new DSC finite element scheme was proposed and implemented to overcome the numerical difficulties. The finite element thermoplastic formulation was modified and implemented based on Drucker's postulate. Thermoplastic deformation and viscoplastic deformation usually happen sequentially or combined. An alternative finite element computational method for viscoplastic problem was proposed and the FE program is modified. Computational examples show the new procedures produce accurate and consistent results and the program is robust. Material parameters for the HISS and DSC models were used to back predict the rate and temperature dependent test results using the modified finite element program. These back predictions showed that the HISS and DSC constitutive models and the FE program can be used to accurately simulate solder joint material behavior and predict solder joint damage and failure.

Η εργασία αυτή έχει ως σκοπό να αναπτύξει το ρόλο της συσκευασίας και τα χαρακτηριστικά της, καθώς και την σημασία αυτής για τους καταναλωτές. Ειδικότερα στο πρώτο κεφάλαιο, αναλύονται τα βασικά στοιχεία που αφορούν την συσκευασία των προϊόντων, ο ρόλος της καθώς και η διαδικασία σχεδιασμού αυτής. Στο δεύτερο κεφάλαιο, αναφέρονται οι αρχές και οι λειτουργίες της συσκευασίας. Στη συνέχεια, στο τρίτο κεφάλαιο, παρουσιάζονται τα χαρακτηριστικά της συσκευασίας, όπως επίσης και τα σημεία ώστε να είναι επιτυχημένη μια συσκευασία. Στο τέταρτο κεφάλαιο της εργασίας, αναπτύσσονται στοιχεία που αφορούν τη σχεδίαση της συσκευασίας και τις «νέες» συσκευασίες. Επιπρόσθετα, στο πέμπτο κεφάλαιο, αναλύονται όλα τα στοιχεία τα οποία θα πρέπει να αναγράφονται στην συσκευασία και παρουσιάζονται κάποια ζητήματα σχετικά με την ανάπτυξη της. Τέλος, διεξήχθη μελέτη στην Αττική Μελισσοκομική Εταιρεία, με σκοπό την αναγραφή του σήματος «e» στις συσκευασίες των προϊόντων ώστε να διασφαλισθεί η ποιότητα και η αξιοπιστία της εταιρείας. / This thesis aims to develop the role of the packaging and its features, as well as the importance of, for the consumers. Especially in the first chapter, analyzing the key elements relating to product packaging, the role and the design process of this. In the second chapter, it been referred to the authorities and functions of packaging. Then, in the third chapter, the characteristics of the packaging were analyzed, as well as the points to be a successful package. In the fourth chapter of the thesis, was developed evidence concerning the design of the packaging and the "new" packaging. Additionally, in the fifth chapter, analyze all the elements that should be listed on the packaging and presented some issues on the development. Finally, a study was conducted in Attiki Company, in order to indicate the signal «e» on product packaging to ensure the quality and reliability of the company.

Reliability quantification is one of the most important tasks in Reliability Engineering. During the design, development, and operational phase, this information can be very valuable to the product's designers, and users. The designers can use it to guide their design, find the design's weak points. Users can use it to setup maintenance plans and schedule. PCBs, as the major building block of electronic equipment, have been widely used in modern complex systems, such as aircraft, automotives, laptop computers, etc. Its reliability plays a vital role in the whole system's reliability. Thus, effective and accurate quantification of PCB's reliability becomes very essential to the whole electronic system's reliability quantification. Random vibration and thermal cycling are two common environments experienced by PCB's. As a result, quantifying the reliability of a PCB under these two environments becomes necessary. Currently, in industry, the commonly used methods to quantify the reliability of a PCB are the MIL-HDBK-217 and Bellcore type methods. However, the lack of accuracy and slow pace of updating the databases have limited the usage of these methods. In this dissertation, a Modified Stress-Strength Interference (MSSI) method is proposed to quantify the reliability of a PCB. In this method, not only the stress and the strength are assumed to be distributed, but also is the mean value of the strength, so that both the initial designed-in reliability and the reliability at any time can be quantified. Based on this method, a reliability quantification model for the PCB is developed. In this model, a PCB is divided into three parts: i.e., board, interconnects, and parts and modules mounted on the board. Seven (7) failure modes related to the board and the interconnects, and one (1) failure mode related to the module have been investigated. The dependence between these failure modes is studied and incorporated into the reliability quantification model. A three-step popcorn effect reliability quantification model is also proposed by means of considering the failure mechanism of the popcorn effect. Finally, a comprehensive example is given to demonstrate the usage of the methodology proposed in this dissertation.

Temperature cycling and random vibration have proven to be the two most effective environmental stress screens. This study presents an extensive research on the physical quantification and optimization of temperature cycling and random vibration screens. For temperature cycling screen, a general model has been proposed to describe a typical temperature response cycle and a typical power-temperature response cycle. The least-squares parameter estimates for the two modified Arrhenius models are derived. Two general models for quantifying the equivalent aging acceleration factor of a typical temperature cycle with or without power cycling, considering both reaction rate stress and temperature change rate stress and also incorporating the temperature dependence of the activation energy, are derived. A closed form solution under the mixed-exponential life distribution assumption and an iteration equation solution under the Weibull distribution assumption, of the optimum number of temperature cycles for a specified post-screen field Mean Residual Life (MRL) goal, are established. For the random vibration screen, the distributions of the cumulative damage and fatigue life, under both stationary narrow-band and stationary wide-band random stressings, are derived under both-normal, semi-normal, and Markov-process assumptions. A bimodal mixed P-S-N diagram is proposed, from the failure physics point of view, to describe the fatigue strength of a non-screened unit. The concepts of the threshold S-N curve and the screening probability for fatigue defect precipitation are proposed to facilitate the quantification of random vibration screens. Finally, the closed form solution of the optimum vibration duration for a specified screening probability is derived under both-normal, semi-normal and Markov-process assumptions, respectively.

Experiments were performed to characterize the conjugate heat transfer due to a square flush heat source mounted at the center of a square horizontal plate in a small horizontal enclosure. The plate area was six times larger than the heat source area. Three different plates with heat source facing upwards were considered: a 25mm balsa wood plate which provided a nearly adiabatic surface, a 1.57mm thick FR-4 plate with no copper, and a 1.57mm thick FR-4 plate with a single layer of 0.036mm thick copper cladding on source side. The back of the board was insulated for all cases. The experimental exploration included measurement of heat transfer coefficient over the heat source, plate surface temperature distribution and temperature distribution in the air volume above the plate. The heat transfer coefficients exhibited distinct behavior at high aspect ratios in which the dominant length scales were related to the source. At intermediate aspect ratios, length scales for both source and enclosure were relevant, and at small aspect ratios, a conduction limit was observed, which was dependent on board conductivity. The heat transfer coefficients at high aspect ratios exceeded by 14% the prior correlations for upward facing isolate plates, when the ratio of source area to perimeter was used as the significant length scale, and a stronger dependence than Ra1/4 was measured. Classical correlations for shallow differentially heated enclosure were not satisfactory in describing the dependence on enclosure height. With increasing board conductivity, board thermal spreading increased the effective source size so that the discretely heated board heat transfer coefficients tended towards the behavior of the classical uniformly heated board. New first-order thermal design formulae were derived for determining peak temperatures of sources on conducting substrates, and for determining the associated thermal "zone of influence" or "footprint." The board heat spreading was accounted for by using its effective "thermal footprint" radius and correlations for conjugate heat transfer based on this length scale were successful in describing the behavior of the average Nusselt number at large enclosure heights. Some qualitative flow visualization was also performed and representative results are shown.

Failure of materials and interfaces are commonly linked to the fracture parameters such as the stress intensity factors and the energy release rate. However, there exists no experimental procedure for the direct measurement of these fracture parameters. This dissertation reports on the development of a new technique to obtain these parameters by testing specimens created from post-production electronic packages. The results from the experimental testing are then used as the input for an analytical model which computes the desired parameters. The specimens are thin strips of post production electronic packages. A crack is introduced along the interface in the specimen. Loading is applied to the specimen using the bend fixture inside the chamber of a scanning electron microscope, and images are captured following each load step. Digital image analysis on these images provides the displacement field around the crack tip to be used as boundary conditions in the analytical model. A hybrid formulation is developed utilizing the exact solution for the stress and displacement fields based on the eigenfunction expansion method under general loading. The region has two dissimilar elastic or viscoelastic material wedges with perfect bonding, and is not limited to a particular geometric configuration. The solution method is based on the principle of virtual work in conjunction with the use of Laplace transformation to eliminate time dependency. The strength of the singularity is obtained in the time space without resorting to approximate Laplace inversion techniques. However, the intensification of the stress components is obtained by employing an approximate inversion technique. One of the main contributions of this dissertation is the development of multiple techniques for the creation of test specimens from electronic packages. These methods involve different procedures of encapsulation for sectioning and techniques for the introduction of the crack to the interface. A second development is the technique of testing using image capture in conjunction with digital image correlation to find localized displacements. The third contribution from this work is the development of an analytical model to accurately model the region near the junction of two dissimilar viscoelastic materials.

No description available.

Forced convection cooling process is the most widely used method of cooling to extend shelf life of horticultural produce after harvest. However, heterogeneous cooling of produce inside different parts of ventilated packages is a serious problem. Therefore, it is essential to design packages that facilitate air circulation throughout the entire package to provide uniform cooling. Selection of appropriate combinations of air temperature and velocity for a given vent design is currently done largely by experimental trial and error approach. A more logical approach in designing new packages, to provide uniform cooling, is to develop mathematical models that would be able to predict package performance without requiring costly experiments. / In this study, mathematical models of simultaneous airflow, heat and mass transfer during forced convection cooling process were developed and validated with experimental data. The study showed that produce cooling is strongly influenced by different ventilated package designs. Generally, cooling uniformity was increased by increasing number of vents from 1 (2.4% vent area) to 5 (12.1% vent area). More uniform produce cooling was obtained at less cooling time when vents were uniformly distributed on package walls with at least 4.8% opening areas. Aerodynamic studies showed that heterogeneity of airflow distribution during the process is strongly influenced by different package vent configurations. The highest cooling heterogeneity index (108%) was recorded at 2.4% vent area whereas lowest heterogeneity index (0%) was detected in a package with 12.1% vent area. / The magnitudes of produce evaporative cooling (EC) and heat generation by respiration (HG) as well as the interactive effects of EC, HG and package vent design on produce cooling time were also investigated. Considerable differences in cooling times were obtained with regard to independent and simultaneous effects of EC and HG in different package vent configurations. Cooling time was increased to about 47% in a package with 1 vent compared to packages with 3 and 5 vents considering simultaneous effects of EC and HG. Therefore, the effects of EC and HG can be influential in designing the forced-air precooling system and consequently, in the accurate determination of cooling time and the corresponding refrigeration load.

Almost everything we as consumers buy in a store has a package. Packages have many functions – some, if not all, present marketers with the opportunity to gain competitive advantages. The packaging influences the usage behavior long after it has influenced the purchase, therefore it is an interesting empirical context to study within the field of marketing. Nevertheless, academic attention to packaging has been sparse over the last two decades even though the industry focus on packaging as a strategic tool has grown over that same period. Exceptions in the marketing literature are investigations of packaging and brand communication, advertisement-package coordination, and packaging size and shape. In contrast to the traditional approach that views packaging as a complimenting non-product-related attribute, it is suggested in this thesis that packaging is a product-related attribute that does affect the customers’ experiences of products. The overall aim of this thesis is to develop and test theoretical models and provide empirical evidence of customer experiences in the context of packaging from a service perspective. To study packaging from a service perspective is relevant for several reasons. One reason is that packaging can have several functions, which include more than the physical package. Another reason is that packages are carriers of information that is interpreted by customers. The combination of function, information, the physical package, and its content creates the total customer experience. The results of this thesis provide increased knowledge about packaging and customer experiences from a service perspective. On an attribute level, quality attributes such as protection and usability are categorized according to Kano’s theory of attractive quality. The results show that customers’ evaluations of packages are multi-dimensional. On a comprehensive or an overall level, structural equation modeling is used to investigate the consumption process. We conclude that the quality attributes of packages need to be designed to display quality both on the shelf in a store and during usage and consumption at both the attribute and comprehensive level.