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At least 163 records · Page 9Linked to original sources
PubMed2001

A chassis test procedure to mimic the heavy-duty engine transient emissions certification test.

In-use emissions from vehicles using heavy-duty diesel engines can be significantly higher than the levels obtained during engine certification. These higher levels may be caused by a combination of degradation of engine components, poor engine maintenance, degradation or failure of emissions after-treatment devices, and engine and emissions system tampering. A direct comparison of in-use vehicle emissions with engine certification levels, however, is not possible without removing an engine from the vehicle in order to perform engine dynamometer emissions testing. The goal of this research was to develop a chassis test procedure that mimics the engine performance, and as such the expected emissions levels, from the engine certification emissions test prescribed in the U.S. Code of Federal Regulations. Emissions measurements were taken from two engines during testing on an engine dynamometer using the transient heavy-duty Federal Test Procedure (FTP). Additionally, each engine was installed in an appropriate vehicle, and emissions measurements were taken using a chassis dynamometer while employing a vehicle driving schedule intended to match closely the instantaneous torque and speed schedule of the engine FTP. Engine and chassis testing was performed with the engines in stock (unmodified) condition as well as in several modes to simulate either tampered or poorly maintained conditions. The use of a chassis test as a predictive tool for determining whether an engine in a vehicle would pass the engine certification test has proven to be worthwhile. Analysis of the data shows that identification of chassis-mounted engines with NOx emissions above certification levels is possible by employing engine-specific correction factors. In the case of PM emissions, significant data scatter allowed only the identification of gross PM emitters. Engine tampering and poor maintenance can raise PM and NOx emissions, and these increases can be correctly identified by a chassis test. Analysis of chassis and engine CO and HC emissions did not reveal a strong enough correlation to warrant the use of the chassis test for emissions screening of these two pollutants.

Air Pollution↗
PubMed2006

Teaching ethics in engineering education through historical analysis.

The goal of this paper is to stress the significance of ethics for engineering education and to illustrate how it can be brought into the mainstream of higher education in a natural way that is integrated with the teaching objectives of enriching the core meaning of engineering. Everyone will agree that the practicing engineer should be virtuous, should be a good colleague, and should use professional understanding for the common good. But these injunctions to virtue do not reach closely enough the ethic of the engineer as engineer, as someone acting in a uniquely engineering situation, and it is to such conditions that I wish to speak through a set of specific examples from recent history. I shall briefly refer to four controversies between engineers. Then, in some detail I shall narrate three historical cases that directly involve the actions of one engineer, and finally I would like to address some common contemporary issues. The first section, Engineering Ethics and the History of Innovation, includes four cases involving professional controversy. Each controversy sets two people against each other in disputes over who invented the telegraph, the radio, the automobile, and the airplane. In each dispute, it is possible to identify ethical and unethical behavior or ambiguous ethical behavior that serves as a basis for educational discussion. The first two historical cases described in "Crises and the Engineer" involve the primary closure dam systems in The Netherlands, each one the result of the actions of one engineer. The third tells of an American engineer who took his political boss, a big city mayor, to court over the illegal use of a watershed. The challenges these engineers faced required, in the deepest sense, a commitment to ethical behavior that is unique to engineering and instructive to our students. Finally, the cases in "Professors and Comparative Critical Analysis" illuminate the behavior of engineers in the design of structures and also how professors can make public criticisms of designs that seem wasteful.

Engineering↗
PubMed2004

Environmental education for all engineers.

Environmental engineering education at universities is a rapidly changing field globally. Traditionally it has resided in the civil engineering program addressing water and wastewater quality, treatment, design and regulatory issues. In recent years environmental engineering has become a much broader field encompassing water, wastewater, soil pollution, air pollution, risk assessment, ecosystems, human health, toxicology, sustainable development, regulatory aspects and much more. The need to introduce environmental engineering/green engineering/pollution prevention/design for the environment concepts to undergraduate engineering students has become recognized to be increasingly important. This need is being driven in part through the US Engineering Accreditation Commission Accreditation Board for Engineering and Technology criteria 2000. Thus there has been a major shift in environmental engineering education and it no longer resides only within the civil engineering discipline. This paper focuses on the development of innovative curricula for a brand new engineering program at Rowan University that integrates environmental education for all engineers. A common course known as "engineering clinic" was developed for all engineering students throughout their eight semesters of engineering education. One of the clinic goals is to integrate engineering design and the environment. The program, in its seventh year, indicates successful implementation of environmental education in all four engineering disciplines in their course work and clinics.

Conservation of Natural Resources↗
PubMed2003

"Mind the gaps": an empirical approach to engineering ethics, 1997-2001.

A survey on ethical issues in engineering was administered over a five-year period to Stanford engineering students and practicing engineers. Analysis of its results strongly suggests that important disconnects exist between the education of engineering students regarding ethical issues in engineering on the one hand, and the realities of contemporary engineering practice on the other. Two noteworthy consequences of these gaps are that the views of engineering students differ substantially over what makes an issue an ethical issue, while practicing engineers exhibit significant disagreement over what is the most important non-technical aspect of being a responsible engineering professional in contemporary society. These divergences impede the recognition of ethical issues and of specific moral responsibilities of engineers in concrete professional practice. It is argued that the use of suitably refined and probing surveys of engineering students and practicing engineers about ethical issues in engineering is an important although neglected empirical approach to the study of engineering ethics. Such an approach can enhance the prevailing case study method and combat over-tidy theoretical-analytical approaches to the subject.

Attitude↗
PubMed1991

Cellular engineering.

Cellular engineering applies the principles and methods of engineering to the problems of cell and molecular biology of both a basic and applied nature. As biomedical engineering has shifted from the organ and tissue level to the cellular and sub-cellular level, cellular engineering has emerged as a new area. A cornerstone of much of this activity is cell culture technology, i.e., the ability to grow living cells in the artificial environment of a laboratory. Cellular engineering includes the role of engineering in both basic cell biology research and in the making of products which use living cells, e.g., tissue engineering and bioprocess engineering. The former involves the use of living cells in the development of biological substitutes for the restoration or replacement of function, and the latter the use of living cells to manufacture a biochemical product, e.g., through the use of recombinant DNA technology. In fact, as biomedical engineering has expanded to include the cellular level, and bioprocess engineering has shifted in interest from microbial organisms to include mammalian cells, there are intellectual issues in which an interest is shared by these two formerly separate areas of engineering activity. Cellular engineering thus transcends the field of biomedical engineering.

Biomedical Engineering↗
PubMed1998

Creation of viable pulmonary artery autografts through tissue engineering.

BACKGROUND: "Repair" of many congenital cardiac defects requires the use of conduits to establish right ventricle to pulmonary artery continuity. At present, available homografts or prosthetic conduits lack growth potential and can become obstructed by tissue ingrowth or calcification leading to the need for multiple conduit replacements. Tissue engineering is an approach by which cells are grown in vitro onto biodegradable polymers to construct "tissues" for implantation. A tissue engineering approach has recently been used to construct living cardiac valve leaflets from autologous cells in our laboratory. This study assesses the feasibility of a tissue engineering approach to constructing tissue-engineered "living" pulmonary artery conduits. MATERIALS AND METHODS: Ovine artery (group A, n = 4) or vein (group V, n = 3) segments were harvested, separated into individual cells, expanded in tissue culture, and seeded onto synthetic biodegradable (polyglactin/polyglycolic acid) tubular scaffolds (20 mm long x 15 mm diameter). After 7 days of in vitro culture, the autologous cell/polymer vascular constructs were used to replace a 2 cm segment of pulmonary artery in lambs (age 68.4 +/- 15.5 days, weight 18.7 +/- 2.0 kg). One other control animal received an acellular polymer tube sealed with fibrin glue without autologous cells. Animals were sacrificed at intervals of 11 to 24 weeks (mean follow-up 130.3 +/- 30.8 days, mean weight 38.9 +/- 13.0 kg) after echocardiographic and angiographic studies. Explanted tissue-engineered conduits were assayed for collagen (4-hydroxyproline) and calcium content, and a tissue deoxyribonucleic acid assay (bis-benzimide dye) was used to estimate number of cell nuclei as an index of tissue maturity. RESULTS: The acellular control graft developed progressive obstruction and thrombosis. All seven tissue-engineered grafts were patent and demonstrated a nonaneurysmal increase in diameter (group A = 18.3 +/- 1.3 mm = 95.3% of native pulmonary artery; group V = 17.1 +/- 1.2 mm = 86.8% of native pulmonary artery). Histologically, none of the biodegradable polymer scaffold remained in any tissue-engineered graft by 11 weeks. Collagen content in tissue-engineered grafts was 73.9% +/- 8.0% of adjacent native pulmonary artery. Histologically, elastic fibers were present in the media layer of tissue-engineered vessel wall and endothelial specific factor VIII was identified on the luminal surface. Deoxyribonucleic acid assay showed a progressive decrease in numbers of cell nuclei over 11 and 24 weeks, suggesting an ongoing tissue remodeling. Calcium content of tissue-engineered grafts was elevated (group A = 7.95 +/- 5.09; group V = 13.2 +/- 5.48; native pulmonary artery = 1.2 +/- 0.8 mg/gm dry weight), but no macroscopic calcification was found. CONCLUSIONS: Living vascular grafts engineered from autologous cells and biodegradable polymers functioned well in the pulmonary circulation as a pulmonary artery replacement. They demonstrated an increase in diameter suggesting growth and development of endothelial lining and extracellular matrix, including collagen and elastic fibers. This tissue-engineering approach may ultimately allow the development of viable autologous vascular grafts for clinical use.

Animals↗
PubMed2002

Prediction of in-use emissions of heavy-duty diesel vehicles from engine testing.

A model of a heavy-duty vehicle driveline with automatic transmission has been developed for estimating engine speed and load from vehicle speed. The model has been validated using emissions tests conducted on three diesel vehicles on a chassis dynamometer and then on the engines removed from the vehicles tested on an engine dynamometer. Nitrogen oxide (NOx) emissions were proportional to work done by the engine. For two of the engines, the NOx/horsepower(HP) ratio was the same on the engine and on the chassis dynamometer tests. For the third engine NOx/HP was significantly higher from the chassis test, possibly due to the use of dual engine maps. The engine certification test generated consistently less particulate matter emissions on a gram per brake horsepower-hour basis than the Heavy Duty Transient and Central Business District chassis cycles. A good linear correlation (r2 = 0.97 and 0.91) was found between rates of HP increase integrated over the test cycle and PM emissions for both the chassis and the engine tests for two of the vehicles. The model also shows how small changes in vehicle speeds can lead to a doubling of load on the engine. Additionally, the model showed that it is impossible to drive a vehicle cycle equivalent to the heavy-duty engine federal test procedure on these vehicles.

Automobile Driving↗
PubMed2002

Autologous tissue-engineered trachea with sheep nasal chondrocytes.

OBJECTIVE: This study was designed to evaluate the ability of autologous tissue-engineered trachea shaped in a helix to form the structural component of a functional tracheal replacement. METHODS: Nasal septum were harvested from six 2-month-old sheep. Chondrocytes and fibroblasts were isolated from tissue and cultured in media for 2 weeks. Both types of cells were seeded onto separate nonwoven meshes of polyglycolic acid. The chondrocyte-seeded mesh was wound around a 20-mm-diameter x 50-mm-long helical template and then covered with the fibroblast-seeded mesh. In 2 separate studies the implants were placed either in a subcutaneous pocket in the nude rat (rat tissue-engineered trachea) or in the neck of a sheep (sheep tissue-engineered trachea). Rat tissue-engineered tracheas were harvested after 8 weeks and analyzed by means of histology and biochemistry. Sheep tissue-engineered tracheas were harvested from the neck at 8 weeks and anastomosed into a 5-cm defect in the sheep trachea. RESULTS: Sheep receiving tissue-engineered trachea grafts survived for 2 to 7 days after implantation. Gross morphology and tissue morphology were similar to that of native tracheas. Hematoxylin-and-eosin staining of rat tissue-engineered tracheas and sheep tissue-engineered tracheas revealed the presence of mature cartilage surrounded by connective tissue. Safranin-O staining showed that rat tissue-engineered tracheas and sheep tissue-engineered tracheas had similar morphologies to native tracheal cartilage. Collagen, proteoglycan, and cell contents were similar to those seen in native tracheal tissue in rat tissue-engineered tracheas. Collagen and cell contents of sheep tissue-engineered tracheas were elevated compared with that of normal tracheas, whereas proteoglycan content was less than that found in normal tracheas. CONCLUSIONS: This study demonstrated the feasibility of recreating the cartilage and fibrous portion of the trachea with autologous tissue harvested from single procedure. This approach might provide a benefit to individuals needing tracheal resection.

Animals↗
PubMed1976

[Successes and prospects for genetic engineering].

The review of literature (1970-1976) on problems of gene engineering is given. Gene engineering is pointed out to be a new method of modern biology and a new page of modern molecular genetics. Gene engineering detected a real possibility of artificial creating living hybrid organisms, i.e. constructing functional recombinant DNA molecules according to a project of investigator, but not to possibilities of crossing. The determination of gene engineering (in contrast with genetical engineering) is given in the first division of the article. Genetical engineering is a construction of hybrid organisms on the basis of recombination between non-homologous chromosomes cy crossing. Genetical engineering is based on sex crossing, thus the application of this method is restricted by crossability (i.e. experiments in vivo), which possibilities are determined by taxonomical limits. Gene engineering is a new method of operating directly with genes. It permits constructing in vitro any hybrid genomes desirable. There is no limits of combining ability for gene engineering. Three main stages of constructing hybrid genomes should be taken into account for the proper determination of gene engineering as a method of genome constructing: 1) the gene isolation; 2) their cross-linking in vitro; 3) the transfer of hybrid DNA into recipient cell or its genome. The cardinal stage of gene engineering is the construction of hybrid DNA, cross-linking any initial DNAs from any remote animals, plants and bacteria. All the methods known of gene isolation are described. The chemical method of gene isolation is based on that case, when DNA of some gene differs in its physico-chemical characteristics from total DNA, for example, DNAs of genes coding ribosomal RNAs or sea urchine histone DNA. Isolation of promotors and operators using DNA dependent RNA polymerase, which recognizes promotors, repressor and operator DNA, should also be considered as the chemical method of gene isolation. Restrictase method, which is also well known, is convenuent because the restricts have long enough sticky ends, which is important for the following gene cross-linking. The method of total restriction, reported by Lederberg et al. and Debabov et al., is described. The phage method (in particular, Shimada method) is given, permitting the direct integration of lambda phage into a number of sites of Escherichia coli chromosome. Gene engineering method of gene isolation is mentioned, in particular, the data of Kameron et al. on hybrid phages carrying DNA ligase gene, and Clark a. Carbon on hybrid plasmids carrying triptophane and arabinose operons genes. These methods are called "shot gun". Methods of gene isolation from higher organisms are less developed. A method of gene isolation using so called colony hybridization (according to Grünstein and Hognes) is also given...

Bacteriophages↗