This study tested a dynamic traffic assignment (DTA) model as a tool for pre-planning strategies for managing major freeway incidents. Incidents of varying scale and duration were modeled in the northern Chicago highway network, and the impacts of incidents and response actions were measured in terms of both lane-mile-hours of...
This presentation contains information about the project "The future of transportation... and how we'll pay for it" by Joseph L. Schofer, Department f Civil & Environmental Engineering. The presentation was delivered at the 40th Anniversary Seminar Day at Northwestern University on April 18, 2009.
Gentrification - the process in which higher income (and often younger) households displace lower income residents of a city neighborhood - has been occurring in many urban neighborhoods over the last few decades. This process changes the demographics, and often the essential character, of the neighborhood. As a result, we...
This presentation contains information on the project "Aligning Data to Support Transportation Decisions, Emerging Challenges & Opportunities for the Data World". The presentation was delivered by Joseph L. Schofer at Transportation Research Board – AASHTO Peer Exchange meeting on May 15-16, 2008.
The paper deals with the behavior of fluid cement pastes, formulated from Self Consolidating Concretes (SCCs), and the experimental correlation of fundamental rheological properties, such as the yield stress and the viscosity, with measurements from field tests, such as the mini-cone slump flow test. As a matter of fact, several...
The concrete currently used in the slip-form paving process is a low slump concrete that requires both internal and external vibration in order to achieve satisfactory compaction. The use of vibrator fingers for the internal vibration often leads to trails on the surface of the pavement and to segregation around...
The setting and hardening process of concrete can be considered as the most critical time period during the life of a concrete structure. To assure high quality and avoid problems in performance throughout the life of the material, it is essential to have reliable information about the early age properties...
This presentation contains information on the keynote paper "Health Monitoring of Early Age Concrete". The presentation was delivered by Surendra P. Shah at CONSEC'04 in Seoul, Korea on June 30, 2004.
In this paper, the correlation of reflection loss measured by an ultrasonic shear wave reflection
method and the microstructure in cement-based material is investigated. Three cement pastes
(Portland cement type I) with different water-cement ratios (0.35, 0.50 and 0.60) cured at 25
°C were examined. The ultrasonic shear wave reflection...
The gradual evolution of the material properties of a cement-based material, i.e. the stiffness of cement paste, is the result of the continuous change of the microstructure with the progress of the hydration process. Based on an existing micromechanical model for the simulation of the shear and elastic modulus of...
The Center for Advanced Cement-Based Materials (ACBM) is a consortium of researchers from: Northwestern University, University of Illinois at Urbana-Champaign, Purdue University, The University of Michigan, and The National Institute of Standards and Technology. This ACBM update contains information on the article "A better Maturity Meter?" by Surendra P. Shah...
The setting and hardening process of concrete is considered to be the most critical time period during the life of a concrete structure. Previous research has been conducted on an ultrasonic wave reflection method that utilizes a steel plate embedded in the concrete to measure the reflection loss of shear...
The nondestructive, in-situ testing of early-age concrete properties is a crucial point for the progress of many construction projects in the building sector. The application of such techniques can establish e.g. the earliest possible form removal from concrete construction elements, thereby opening highways to traffic or releasing prestress from steel...
This paper describes proposed schemes for describing and indexing two image collections and requirements for the software that would give the end-user access to thesaurus terms and a graphical display of the faceted classification structures of indexing records. Editorial cartoons comprise one collection, dance videos the other.
The Avalon Media System (Avalon) provides access and management for digital audio and video collections in libraries and archives. The open source project is led by the libraries of Indiana University Bloomington and Northwestern University and is funded in part by grants from The Andrew W. Mellon Foundation and Institute...
The U.S. has 542,000 bridges that consume billions of dollars per year in construction, rehabilitation and maintenance funds and which are the lifelines of U.S. commerce. The 1992 ISTEA (fntermodal Surface Transportation Efficiency Act) mandates the implementation of a quantitative computerized bridge management system by I 996. A prime need...
This report describes the results of applying acoustic emission (AE) testing to the trunnion shafts of the East Span of the 1-5 Interstate Bridge. The tests were done at the request of Oregon DOT personnel to determine if active fatigue racks are present in the subject shafts.
The in-depth inspection by WIDOT detected two sites that had visible cracks in the stiffener-to-hanger diaphragm welds, the east side of Hanger 6 in the north tie girder, and the east side of Hanger 4 in the south tie girder. Additionally, many ultrasonic indications were detected by WIDOT in the...
The segmental prestressed concrete box girder of Koror-Babeldaob (KB) Bridge in Palau, which had the record span of 241 m (791 ft.), presents a striking paradigm of serviceability loss due to excessive multi-decade deflections. The data required for analysis have recently been released and are here exploited to show how...
A study is conducted to determine the effects on the early hydration kinetics and
compressive strength by seeding of Portland cement and alkali-activated blast furnace
slag with a pure form of calcium silicate hydrate (C-S-H). The effects of C-S-H seeding
during the early nucleation and growth period of each type...
A qualitative evaluation of the Africa Demos forum from a small group of African scholars and one journalist writing on various topics related to Africa.
Contents:
Volume 1, Number 1;
Volume 1, Number 2;
Volume 1, Number 3;
Volume 1, Number 4;
Volume 1, Number 5;
Volume 2, Number 1;
Volume 2, Number 2;
Volume 2, Number 3;
Volume 3, Number 1;
Volume 3, Number 2;
Volume 3, Number 3;
Volume 3, Number 4;
Volume...
Traditional bottom-up mass spectrometry-based proteomics relies on the use of an enzyme, often trypsin, to generate small peptides (typically < 25 amino acids long). In top-down proteomics, proteins remain intact and are directly measured within the mass spectrometer. This technique, while inherently simpler than bottom-up proteomics, generates data which must...
A longstanding goal of synthetic biology has been the programmable control of cellular functions. Central to this is the creation of versatile regulatory toolsets that allow for programmable control of gene expression. Of the many regulatory molecules available, RNA regulators offer the intriguing possibility of de novo design – allowing...
The issues discussed in this essay - the fundamental objectives of the Nigerian state, public accountability, and a code of conduct for state officials - have been central concerns throughout its post- colonial history. Underlying these debates have been differing views about the best political economy model for Nigeria. The...
A half-century of high revenues from petroleum export has failed to elevate more than a small percentage of Nigerians above the poverty level. The failure to manage the vicissitudes of global oil markets, and to grow other sectors of the economy, has led to constant budget deficits and unsustainable national...
In the years preceding the 1979 national elections, ideology featured prominently in political debates and consultations regarding the new constitutional order. Proponents of a social democratic system were particularly prominent. However, the actual formation of political parties, governed by the new requirements for national representation, and the resurgence of veteran...
The 1979 Nigerian elections reflected the dedication of Nigerians to pursue democratic governance and the severe challenges to be overcome. The sweeping victory of the NPN, and the election of Alhaji Shehu Shagari as president, required a last-minute manipulation of the formula for achieving victory in the first round. After...
The building of a trans-ethnic political space, and a nation that commands the loyalty of the country’s citizens, have been persistent aspirations of Nigerian governments. The 1979 elections demonstrated that, however much political party leaders may seek to build a national following, they are “trapped” by ethnic and other sectional...
The building of the Second Republic required a military government, which had been deeply engaged in shaping the Federation over almost fifteen years, performing as an impartial umpire in the electoral choice of its successors. This complex process is dissected in this article together with an analysis of the relative...
This article resumes the exploration of Nigeria’s political economy and the entrenchment of a prebendal mode of attitudes and behaviors. It takes up the shift to a mono-mineral export economy, the socio- economic proclivities of the dominant class, the considerable expansion in the state’s economic role, and the distinct pattern...
The forcible ending of Nigeria’s second attempt at constitutional civilian rule since independence in 1960 is a mixed story. The 1983 general elections were tarnished by violence and fraud. They took place in a context of economic decline and policy disarray. However, the opposition still retained an important share of...
In this essay, key features of Nigerian governance since independence are reviewed. The military had ruled the county for thirteen years and civilian politicians, in two phases, had done so for ten. Military governments involved significant participation by civilians, so there was overlap between these successive systems. Moreover, the military...
The custom of voluntarily tipping for services rendered has gone in and out of fashion in America since its introduction in the 19th century. Restaurant owners that ban tipping in their establishments often claim that social justice drives their decisions, but we show that rational profit-maximization may also justify the...
Cracking is one of the most common concerns cited by owners of structures adjacent to construction or mining blasting. While a large database of case studies documenting the relative insignificance of ground motion induced by responsible blasting compared to weather effects on cracks in nearby structures has been established, the...
Most studies of crack response have focused on opening and closing of a crack in the plane of the wall in which the crack occurs. Crack movement also occurs perpendicular or normal to the plane of the wall. This paper will examine and compare the in-plane and out-of-plane (normal) response...
Surveillance of large geotechnical projects requires autonomous collection of data from a wide range of instrument types. An equally large range of data formats are employed by these measurement systems. A data exchange protocol is needed to make field data available for interpretation on a variety of platforms. This paper...
Blasting and climatological response of cracks are compared for structures constructed of concrete block typical of home construction in Europe. While much has been written comparing micrometer crack response of wood frame structures typical of residential construction in North America, little has been written concerning response of structures more typical...
Carbonation, a neutralizing reaction in cement paste, can be used to date cracks in cementitious materials. Currently, comparison between two cracks is the only method available to predict a relative age with carbonation. These two crack studies require a crack of known age in a similar material with similar exposure...
This paper summarizes micro-inch response of cosmetic cracks in a typical slab-ongrade ranch style house to both construction equipment-induced vibration and environmental (weather) effects. This structure was instrumented, and its response studied as part of the development of an Autonomous Crack Measurement (ACM) system. ACM systems are intended to record...
Concern over construction vibration-induced cracking has led to development of a new approach to vibration monitoring called autonomous crack measurement (ACM) and illustrated in Figure 1. This paper describes the concept as well as sensor performance in the first test house fitted an ACM system. Response of three cracks in...
There have been numerous studies that have aimed at improving the low tensile strength, stiffness, and toughness of cementitious materials. This study aims to show that all of these characteristics can be greatly improved by the addition of ladder scale reinforcement at the nano and micro scale. Carbon nanofibers (CNFs)...
Neuroscience research has made many important contributions to the study of the brain and behavior. Perhaps because of these contributions the general public seems to be easily seduced by neuroscientific explanations. Meaning that when a scientific article is paired with a brain image, the information within the article is automatically...
Which areas of Chicago have greater concentrations of lead in their water and is that associated with environmental racism? Since Chicago is racially segregated, the marginalized areas such as the south side and west side are more likely to contain high levels of lead.
Humans are unique in their ability to think abstractly (e.g. using language, learning relations). Previous work from our lab has shown that infants can learn simple abstract relations, like whether two objects are the “same” or “different”. In this study, we investigated flexibility in early learning. Our question was whether...
Aim to facilitate the production of the treatment by optimizing reproducibility and minimizing cost. Tasks: Find cost/time effective way to reach end product, Perfecting technique to increase yield, Adjusting known procedure when necessary, Molecule compliant with drug-like properties (Lipiphilic, Ingestible, Long half-life)
Research questions: Do students face pressure to choose certain racial identities in different social spheres on campus? What identities are selected in what situations? What struggles are faced by those of more than one race on Northwestern’s campus? What privileges are associated with being a multi-racial student at Northwestern University?...