Minimizing loss in LCD glass manufacturing by cutting pattern optimization based on integer programming

Loss reduction plays a critical role in improving both process efficiency and overall profitability. As processes become more complex, loss reduction becomes more challenging and systematic decision-supporting methods are thus needed. This paper illustrates such a method in the context of liquid crystal display (LCD) glass production, which involves a series of chemical processes. Loss-minimizing integer programming models are proposed to compute a cutting pattern that allocates multiple demands to LCD mother glass. Numerical examples from actual LCD glass processes are presented to illustrate the applicability of the proposed method.     

Effect of Segment Scale in a Pore Network of Porous Materials on Drying Periods

Drying periods of porous glass disks of nonhygroscopic MPG glass and hygroscopic Vycor glass were investigated. A simple model of dimensionless segment sizes is proposed where a dimensionless segment size is equal to the value of the tortuosity factor of gas diffusion. This model was applied to the estimation of the segment size and the drying periods of a porous Vycor glass disk. The drying rate curve of the Vycor glass disk showed that the first falling rate period appeared to be included in the constant rate period and that the second falling rate period started right after the constant rate period ended, whereas the drying rate curve of the MPG glass disk estimated from previous models showed that the first falling rate period and the second falling rate period were clearly distinguished. The difference in drying periods between two porous glass disks was caused by a large difference in the respective segment sizes.     

Sorption and transport in glassy polymers–a review

After defining Fickian diffusion in rubbery polymers an overview of transport behavior in polymers is presented. Diffusion and sorption below the glass transition are discussed, followed by a review and classification of the various theoretical models which have been proposed to account for these phenomena. A short list of recommendations for future work is included.     

Designing optical glasses by machine learning coupled with a genetic algorithm

Engineering new glass compositions have experienced a sturdy tendency to move forward from (educated) trial-and-error to data- and simulation-driven strategies. In this work, we developed a computer program that combines data-driven predictive models (in this case, neural networks) with a genetic algorithm to design glass compositions with desired combinations of properties. First, we induced predictive models for the glass transition temperature (T_g) using a dataset of 45,302 compositions with 39 different chemical elements, and for the refractive index (n_d) using a dataset of 41,225 compositions with 38 different chemical elements. Then, we searched for relevant glass compositions using a genetic algorithm informed by a design trend of glasses having high n_d (1.7 or more) and low T_g (500 °C or less). Two candidate compositions suggested by the combined algorithms were selected and produced in the laboratory. These compositions are significantly different from those in the datasets used to induce the predictive models, showing that the used method is indeed capable of exploration. Both glasses met the constraints of the work, which supports the proposed framework. Therefore, this new tool can be immediately used for accelerating the design of new glasses. These results are a stepping stone in the pathway of machine learning-guided design of novel glasses.     

Long-term scheduling of a single-unit multi-product continuous process to manufacture high performance glass

In this paper we address the long-term scheduling of a real world multi-product single stage continuous process for manufacturing glass. This process features long minimum run lengths, and sequence dependent changeovers of the order of days, with high transition costs. The long-term scheduling involves extended time horizons that lead to large scale mixed-integer linear programming (MILP) scheduling models. In order to address the difficulties posed by the size of the models, three different rolling horizon algorithms based on different models and time aggregation techniques are developed. The models are based on the continuous time slot MILP model, and on the traveling salesman model proposed by Erdirik-Dogan and Grossmann (2008). Due to the particular characteristics of the process under study, several new features, including minimum run lengths and changeovers across due dates, are proposed. The performance and characteristics of the proposed rolling horizon algorithms are discussed for one industrial example.     

A micromechanical model for quasi-brittle compressive failure of glass-microballoons/thermoset-matrix syntactic foams

We propose a micromechanical model for the quasi-brittle failure of syntactic foams subject to uniaxial compression. We focus on a failure characterised by shear bands inclined of about 45° with respect to the loading axis, often observed in thermoset polymers filled with glass microballoons. Our objective is to develop a three-dimensional Finite Element (FE) model for the effective compressive strength. Towards this aim, we extend our previous FE models, which include fifty randomly placed balloons and were developed to assess the accuracy of linear elastic homogenisation procedures for syntactic foams. Here, we account for the filler polydispersion and introduce a novel structural failure criterion for the glass microballoons. The proposed models are shown to be macroscopically isotropic with respect to the effective strength. We find good agreement with experimental results from the literature on syntactic foams with filler volume fraction of 60%, for which we assume the matrix to be linear elastic.     

The selection and performance of adhesives for a steel–glass connection

Frame-supported glass structures such as curtain walls consist of glass infill plates mounted onto a framework of metallic elements. The longitudinal shear transfer at the interface of the glass and the metal is generally insufficient to mobilise composite action between the two materials, thereby making the units structurally inefficient. In this paper we investigate five candidate adhesives for load bearing steel–glass connections by means of mechanical testing and numerical modelling. The mechanical tests on representative steel–glass connections provide useful data for the selection of a suitable adhesive. The systematic characterisation of the time-dependent constitutive models of the bulk adhesives provides data essential for analytical and numerical models. Good agreement between the experimental results and the numerical models provides a basis for improving the structural efficiency of frame-supported glass structures.     

A Mathematical Model for Amorphous Polymers Based on Concepts of Reptation Theory

Mechanical behaviors of amorphous polymers have been investigated in all aspects from macroscopic thermodynamics to molecular dynamics in past five decades. Most models either have too complex mathematics or can only explain mechanical behaviors of specific materials under certain defined conditions. In this article, a mathematical model is proposed to understand mechanical behaviors of amorphous polymers with aid of the concepts of reptation theory. This new model is capable to match most experimental results of different amorphous polymers for a wide range of time and temperature effect from rubber zone to glassy zone. Above glass transitional temperature, the model shows hyperelastic behavior. Below glass transitional temperature, elastic–viscoplastic properties can be obtained. In the proposed model, no yielding surface is assumed. Hyperelasticity and Mullin's effect are illustrated in a different way without assuming strain energy function in advance. Yielding stress is controlled by Young's moduli, defect density, and defect velocity of molecular chains. Anisotropic plasticity is simply controlled by anisotropic Young's moduli. Therefore, no additional anisotropic parameters are needed to define anisotropic yielding surface. Strain rate, temperature, and hydrostatic pressure effects on yielding stress are through their effect on Young's moduli. Linear elastic, hyperelastic, viscoelastic, and viscoplastic models are put into one single equation, which makes the mathematical structure very easy to understand and easy to use. This model is validated by comparing with five existed experimental data. Proposed model also shares some features similar to the old well‐known large deformation models for amorphous polymers. POLYM. ENG. SCI., 59:2335–2346, 2019. © 2019 Society of Plastics Engineers     

Effect of Small Concentrations of Gallium Oxide on the Structure of Sodium Silicate Glasses

The glass transformation temperatures and de electrical conductivities of sodium silicate glasses with low-level gallia additions have been measured. The composition/property relationships observed in these glasses are different from those observed with larger gallia additions. These trends are discussed in terms of structural models proposed for these glasses.     

Use of neural net models for statistical analysis and regulation of glass ribbon formation on tin melt

A method for constructing and applying neural-net models for analyzing and regulating the conditions for glass ribbon formation on tin melt is examined. In this method models are constructed on the basis of neural nets describing the dependence of the indicators of glass properties on the regime and controllable variable input parameters. An algorithm for adjusting the regime variables as a function of the thickness of the glass ribbon produced is developed taking account of changes occurring in the effects which are under observation.     

Viscosity of glass‐forming systems

As one of the most important properties of glass‐forming liquids, viscosity has drawn significant attention in both glass manufacturing and fundamental research. We review the recent scientific progress in viscosity of glass‐forming systems, including both the liquid and glassy states. After the Vogel‐Fulcher‐Tammann (VFT) equation was introduced, many more efforts have been made to develop more accurate models to describe the temperature dependence of viscosity. In addition to the VFT equation, we also discuss three other viscosity models, viz., the Adam‐Gibbs, Avramov‐Milchev, and Mauro‐Yue‐Ellison‐Gupta‐Allan models. We compare the four viscosity models in terms of their theoretical underpinnings and ability to fit measured viscosity curves. The concept of fragility and the universality of the high‐temperature viscosity limit are also discussed. Temperature‐dependent constraint theory is introduced in detail as a powerful tool for predicting the composition dependence of viscosity. Some examples of the application of this approach to predict the glass transition temperature and fragility of various glass systems are shown. Topological constraint theory is not only of scientific interest, but also has important industrial applicability. We also discuss the thermal history dependence of viscosity in the glassy state. Some phenomenological models are briefly reviewed, while the main focus is given to the modified Mauro‐Allan‐Potuzak model, which can accurately predict the nonequilibrium viscosity as a function of temperature, thermal history, and composition. The correlation of viscosity with elasticity is described in terms of the shoving model. Some theoretical implications of the various viscosity models are discussed, including the concepts of the Kauzmann paradox and the ideal glass transition. Some of the evidence against the existence of these phenomena are discussed. We also review the link between glass relaxation and viscosity, that is, emphasizing that the viscosity equations presented in this review can also be used to model different types of relaxation effects based on the Maxwell relation.     

Formation of films from latices a theoretical treatment

Two published theoretical models for film formation from latices contain errors. These are corrected and new values of the criteria for film formation derived. In Brown's model the error is quite small (less than an order of magnitude) but for Vanderhoff's model the error completely invalidates the analysis. A new model is proposed in which the criterion for film formation is that the latex particles are liquid—a condition fulfilled above the polymer's glass transition temperature.     

Kinetic treatments of glass transition phenomena and viscoelastic properties of glasses

Phenomenological treatments of viscoelasticity and recent models proposed to explain the kinetic aspects of glass transition phenomena are shown to be based on the same underlying physical considerations. This realization suggests the possible unification of these two areas by a single model. This possibility is explored for the simple case of a glass subjected to a single temperature jump followed by a stress relaxation experiment. Presently, sufficient data on any single chemical system to support a critical test of the viability of this model does not exist. Nevertheless, data from several sources on various materials indicate that the qualitative aspects of viscoelastic behavior of glasses at temperatures well below T_g are in accord with the predictions of the unified model.     

采用CAD技术提高玻璃熔窑设计水平

采用优化设计是玻璃熔窑设计技术水平的重要标志。然而，由于窑内复杂的熔化与热工过程，到目前为止，玻璃熔窑仍采用经验设计的方法。由于经验设计存在２若干缺点，导致设计水平难以不断提高，更难以实现优化设计。作者从玻璃熔化工艺和窑炉热工的基本原理出发，宏态的方法，研究与设计方法有关的问题，探求玻璃熔窑诸多主要参数间的关系其数学模型，目前已取得初步成果。熔窑的主要参数由凭经验确定转变为绝大部分通过数学模型计算     

Continuum contact models for coupled adhesion and friction

We develop two new continuum contact models for coupled adhesion and friction, and discuss them in the context of existing models proposed in the literature. Our new models are able to describe sliding friction even under tensile normal forces, which seems reasonable for certain adhesion mechanisms. In contrast, existing continuum models for combined adhesion and friction typically include sliding friction only if local contact stresses are compressive. Although such models work well for structures with sufficiently strong local compression, they fail to capture sliding friction for soft and compliant systems (like adhesive pads), for which the resistance to bending is low. This can be overcome with our new models. For further motivation, we additionally present experimental results for the onset of sliding of a smooth glass plate on a smooth elastomer cap under low normal loads. As shown, the findings from these experiments agree well with the results from our models. In this paper we focus on the motivation and derivation of our continuum contact models, and provide a corresponding literature survey. Their implementation in a nonlinear finite element framework as well as the algorithmic treatment of adhesion and friction will be discussed in future work.     

Simulation Strategy of the Final Dimension in the Glass Pressing Process

The simulation of the final dimension in the glass pressing process is presented in this paper, in which the part contraction and mold deformation are considered as important factors. A thermorheologically simple thermoviscoelastic material model is used to calculate the residual stress. The model for the analysis of contraction is proposed based on the theory of shells, as an assembly of flat elements. The numerical model for the mold deformation is based on a three-dimensional thermoelastic boundary element formulation. Finally, an application example of the picture tube panel is used to verify the presented models and simulation methods.     

Autoclave-free production of water glass

A new autoclave-free technology has been developed for the production of water glass from impure sodium disilicate. A comparative analysis of glass produced using the proposed method and glass obtained by autoclave dissolution has been performed. It is established that the glass produced by the proposed technology is similar in properties to the product of autoclave dissolution.     

Elastic modulus prediction based on thermal conductivity for silica aerogels and fiber reinforced composites

The speed of sound is a critical parameter in the test of mechanical and thermal properties. In this work, we proposed a testing method to obtain the elastic modulus of silica aerogel from the sound speed formulas. The solid thermal conductivity of the silica aerogel is experimentally measured for predicting the sound speeds, and then the elastic modulus is calculated based on the elasticity sound speed model. The experimental data of the solid thermal conductivity of silica aerogels with different densities are employed and the obtained elastic modulus is fitted as a power-law exponential function of the density. Two existing sound speed models and three groups of available experimental data are also employed to validate the present fitting relation, and good agreement is obtained for the silica aerogel in the density range of 150–350 kg/m³. The fitting formula can also be extended to estimate the elastic modulus of the glass fiber-reinforced silica aerogel composite. The results show that the elastic modulus of the aerogel composite is sensitive to the glass fiber volume fraction, while the thermal conductivity is weakly dependent on the glass fiber volume fraction at room temperature in the studied range of fiber volume fraction.     

非晶态粉体玻璃化转变温度的测量方法与装置

为了研究非晶态高分子粉体玻璃化转变与结块特性,需要建立一种实用有效的玻璃化转变温度的测定方法。基于非晶态高分子粉体的体膨胀系数在玻璃化转变时发生突变的原理,采用热膨胀计技术,提出了一种用膨胀计测量非晶态高分子粉体玻璃化转变温度的新方法——膨胀计法,并建立了相应的测量装置。以聚苯乙烯为例,详细介绍了用该方法进行测量及数据处理的过程,并考察了测量结果的有效性。以谷物及含水淀粉体为例,考察了该方法在食品粉体玻璃化转变温度测量中的应用。结果表明,膨胀计法测量非晶态高分子粉体玻璃化转变温度,实用、有效,为非晶态高分子粉体的玻璃化转变温度测量提供了一种新途径。