SOCR: Statistics Online Computational Resource

The need for hands-on computer laboratory experience in undergraduate and graduate statistics education has been firmly established in the past decade. As a result a number of attempts have been undertaken to develop novel approaches for problem-driven statistical thinking, data analysis and result interpretation. In this paper we describe an integrated educational web-based framework for: interactive distribution modeling, virtual online probability experimentation, statistical data analysis, visualization and integration. Following years of experience in statistical teaching at all college levels using established licensed statistical software packages, like STATA, S-PLUS, R, SPSS, SAS, Systat, etc., we have attempted to engineer a new statistics education environment, the Statistics Online Computational Resource (SOCR). This resource performs many of the standard types of statistical analysis, much like other classical tools. In addition, it is designed in a plug-in object-oriented architecture and is completely platform independent, web-based, interactive, extensible and secure. Over the past 4 years we have tested, fine-tuned and reanalyzed the SOCR framework in many of our undergraduate and graduate probability and statistics courses and have evidence that SOCR resources build student's intuition and enhance their learning.

Durable Consumption and Asset Management with Transaction and Observation Costs

The empirical evidence on rational inattention lags far behind the theoretical developments: micro evidence on the most immediate consequence of observation costs - the infrequent observation of state variables - is not available in standard datasets. We contribute to filling the gap with two novel household surveys that record the frequency with which investors observe the value of their financial investments, as well as the frequency with which they trade in financial assets and durable goods. We use these data to test some predictions of existing models and show that to match the patterns in the data we need to modify these models by shifting the focus from non-durable to durable consumption. The model we develop features both observation and transaction costs and implies a mixture of time-dependent and state-dependent rules, where the importance of each rule depends on the ratio of the observation to the transaction cost. Numerical simulations show that the model can produce frequency of portfolio observations and asset trading comparable to that of the median investor (about 4 and 0.4 per year, respectively) with small observation costs (about 1 basis point of financial wealth)and larger transaction costs (about 30 basis points of financial wealth). In spite of its small size the observation cost gives rise to infrequent information gathering (between monthly and quarterly). A quantitative assessment of the relevance of the observation costs shows that the behavior of the investors is essentially unchanged compared to the one produced by a model with transaction but no observation cost. We test a novel prediction of the model on the relationship between assets trades and durable-goods trades and find that it is aligned with the data.

Geopolymers—Design, Preparation, and Applications

Concrete is the most commonly used construction material worldwide, and many efforts have been carried out in recent years to improve its functional properties while also trying to increase its sustainability [...

Engineering characteristics of rocks in Qatar; Applications on excavation and tunneling

Excavation as well as tunneling have become fundamental operations in the advanced civil engineering field. In Qatar, many subsurface construction operations take place in rocks. However, the lack of studies and research that analyze the subsurface rock components from a geotechnical engineering perspective has created unexpected construction conditions. Most of similar studies handled concerns about properties related to oil and gas fields. This research aims to provide a geotechnical study for rocks in Qatar, and to illustrate the impact of the existence of these rock layers on two civil applications; namely excavation and tunneling. During this study, soil investigation reports and rock samples are collected from several bores located in Qatar, and a classification system is utilized to classify the rock samples to identify and study the properties of the existed rocks. Also, numerous production rates from different tunneling and excavation projects are recorded and analyzed, in order to clarify the relation between these rates and the classified rock layers. Based on this analysis, a geotechnical study and mapping system for the rocks in Qatar are presented. Reliable tools for predicting the average productivities of excavation and tunneling projects in Qatar are developed, these tools are aiming to facilitate designing, bidding and executing processes involved with these types of rocks

Support Vector Machines for the Estimation of Specific Charge in Tunnel Blasting

Mine tunnels, short transportation tunnels, and hydro-power plan underground spaces excavations are carried out based on Drilling and Blasting (D&B) method. Determination of specific charge in tunnel D&B, according to the involved parameters, is very significant to present an appropriate D&B design. Suitable explosive charge selection and distribution lead to reduced undesirable effects of D&B such as inappropriate pull rate, over-break, under-break, unauthorized ground vibration, air blast, and fly rock. So far, different models are presented to estimate specific charge in tunnel blasting. In this study, 332 data sets, including geomechanical characteristics, D&B, and specific charge are gathered from 33 tunnels. The data are related to three dams and hydropower plans in Iran (Gotvand, Masjed-Solayman, and Siah-Bishe). Specific charge is modeled in inclined hole cut drilling pattern. In this regard, Support Vector Machine (SVM) algorithm based on polynomial Kernel function is used as a tool for modeling. Rock Quality Designation (RQD) index, Uniaxial Compressive Strength (UCS), tunnel cross-section area, maximum depth of blast hole, and blast hole coupling ratio are considered as independent input variables and the specific charge is considered as a dependent output variable. The modeling results confirm the acceptable performance of SVM in specific charge estimation with minimum error

Complex formations with a block-in-matrix fabric

L'abstract è presente nell'allegato / the abstract is in the attachmen

Properties of Cement Composites Utilizing of Bentonite: A Review

The use of bentonite clay slurries in civil and geotechnical engineering dates back to Veder\u27s pioneering work in 1953. Since then, bentonite has been used for various applications such as the construction of bored piles and diaphragm walls. Plastic concrete walls also require sufficient strength and modulus to adapt to the surrounding environment, and the characteristics and different forms of bentonite commercially available were reviewed in this paper.This paper reviews the properties and applications of bentonite, including its use in cement-bentonite composites for remedial cut-off wall construction. Cement-bentonite grouts offer advantages over bentonite grouts in terms of ease of use and adjustability of strength.Cement-bentonite composites were found to be promising materials for remedial cut-off wall construction due to their ability to meet requirements for strength, stiffness, and permeability. By regulating the mix proportions, the strength of the set grout can be adjusted to match that of the surrounding ground. Cement-bentonite grouts also offer advantages over traditional bentonite grouts, as they are easier to use, offer a longer working period before setting, and can be forgiving if the user deviates from the design formula or the mixing technique. This paper provides useful information for those working with bentonite and cement-bentonite composites in civil and geotechnical engineering applications