Allen H. Hoffman's research while affiliated with Worcester Polytechnic Institute and other places

Publications (38)

Article
Full-text available
Introduction: Arteries can be considered as layered composite material. Experimental data on the stiffness of human atherosclerotic carotid arteries and their media and adventitia layers is very limited. This study used uniaxial tests to determine the stiffness (tangent modulus) of human carotid artery sections containing AHA type II and III lesio...
Article
This paper reports on a real-life study in a US university. In response to financial issues, the administration at an undergraduate tuition-dependent university pushed for growth in student enrollment. The faculty, who argued that the quality of education had been declining, resisted the expansion. More students also affected the use of the univers...
Article
This work in progress describes library research instruction and baseline assessment data in an undergraduate introductory-level mechanical engineering design course. We investigate whether librarian-led information literacy instruction enables students to develop confidence and more creative solutions to their engineering design challenges. Our st...
Article
Accredited engineering programs are required to provide instruction in ethics. A primary goal of ethics education is to develop and improve a student's ability to recognize situations involving ethical decisions and to encourage development of a personal framework by which to decide what to do. A major challenge in ethics education is to personaliz...
Conference Paper
Engineering students need research skills to effectively complete research and design projects; information literacy education during the first year of college positions future engineers to complete projects both during their college years and when they move into their careers. This study provides evidence that faculty-librarian collaboration is an...
Conference Paper
First year project based design courses may face several obstacles. The students have very limited experience in design, construction and realization of prototypes, and in testing and evaluation of their designs. Most first year introduction to engineering courses cover a wide variety of important topics, but lack a strong emphasis on design. Origi...
Conference Paper
Full-text available
This paper reports on a study with a real-life client. In response to budgetary difficulties, administration at a tuition-dependent university pushed for growth in student enrollment. The expansion was resisted by the faculty who argued that the quality of education has declined. More students also impacted the use of university infrastructure. By...
Article
Full-text available
In vivo magnetic resonance image (MRI)-based computational models have been introduced to calculate atherosclerotic plaque stress and strain conditions for possible rupture predictions. However, patient-specific vessel material properties are lacking in those models, which affects the accuracy of their stress/strain predictions. A noninvasive appro...
Conference Paper
Persons with hemiplegia often require a one arm drive wheelchair. Current designs exhibit substantially degraded performance when compared to a standard manual wheelchair. A power-assist, one arm drive wheelchair was developed that was maneuverable, foldable and easy to operate. A motor powers the wheel on the user's affected side, encoders on both...
Conference Paper
The WPI NSF Research Experiences for Teachers (RET) Program involves middle school teachers in authentic design activities that can be translated to the classroom. Middle school teachers often lack design experience, but are now being required to teach the engineering design process. This pilot study used a service learning project to provide two m...
Conference Paper
Project based design courses incorporating realization have an important role in the education of engineering students. Instructor supplied design projects allow students to develop creative solutions. However, these projects largely bypass or eliminate the innovative part of the design process related to recognizing and developing the need for the...
Conference Paper
The number of persons age 65 and older will increase dramatically in the next 2 decades and by 2030 this group will comprise 20% of the U.S. population. Since the incidence of disability increases with age, there will be an increased need for robotic assistive devices. The design process for robotic assistive devices differs significantly from the...
Article
Atherosclerotic plaque may rupture without warning causing heart attack or stroke. Knowledge of the ultimate strength of human atherosclerotic tissues is essential for understanding the rupture mechanism and predicting cardiovascular events. Despite its great importance, experimental data on ultimate strength of human atherosclerotic carotid artery...
Conference Paper
Arteries display highly nonlinear, anisotropic material behavior and can be considered to be a layered composite of fiber oriented materials composed of three layers: intima, media and adventitia. The intima does not affect the material properties of the artery. Thus, the mechanical properties of an artery result from the combined interaction of th...
Article
Introduction An assistive technology device is defined as "any item, piece of equipment or product system whether acquired commercially, off the shelf, modified, or customized that is used to increase, maintain or improve functional capabilities of individuals with disabilities" [1]. Disabilities occur throughout the entire age spectrum and the inc...
Conference Paper
The value of a team approach to design projects has been well established. Projects require teams to demonstrate a wide range of skills including group management, creativity, analysis, manufacturing, testing and communication. Insuring that a team has a sufficient breadth of skills can be problematic. Establishing individual accountability within...
Conference Paper
The function of elevating legrests is to reposition a wheelchair user to increase circulation and to redistribute pressure thereby increasing comfort and minimizing the risk of pressure sores. Three categories of wheelchair users can benefit from elevating legrests; those who cannot sense discomfort in their lower extremities (spinal cord injuries)...
Conference Paper
Ambulatory deficiencies have long been assisted by the use of traditional walkers. However, little attention has been given to the subpopulation with compound impairments such as blindness. This study presents the design of a walker for visually impaired clients, which allows for traditional caning technique. The final prototype, which resulted fro...
Conference Paper
This paper describes the integration of design projects to aid persons with disabilities in the mechanical engineering program at WPI. Students ranging from first year through graduate level design and build a wide range of devices as aids to daily living, to improve mobility, or for use in recreational activities. Ongoing relationships with local...
Article
The level of tissue hydration is known to effect viscoelastic material properties. However, prior studies have not fully investigated the effect of hydration on dynamic behavior nor compared the results of transient and dynamic behavior. The material properties of medial collateral rat knee ligaments were studied in relation to hydration, using (se...
Conference Paper
Mechanoreceptor neurons were studied in an isolated rat skin preparation subjected to dynamic biaxial stretch. The strength of the relationship between neuronal responses and mechanical variables was determined using multiple logistic regression. The experimental protocol allowed the normal stresses as well as the maximum shear stress to be manipul...
Article
A nonlinear systems identification method was used to develop constitutive equations for soft tissue specimens under uniaxial tension. The constitutive equations are developed from a single test by applying a pseudorandom Gaussian (PGN) stress input to the specimen, measuring the resulting strain, and calculating the Volterra–Wiener kernels. First...
Article
A new method was devised to create a stenosis in the rat abdominal aorta. To restrict blood flow, a hemispherical plug was inserted into the aorta through a renal artery. This type of intrinsic (intraluminal) stenosis minimizes possible intramural effects associated with external compression or ligation which severely deform the arterial wall. In t...
Article
The PGN method is used to determine the constitutive equation based upon a single test of short duration. This method is demonstrated to be a viable means of determining constitutive equations for nonlinear viscoelastic soft tissues. Finally, the error in mean strain can be reduced by conducting further refinements to the method.
Article
Deformation and loading of the knee posterior joint capsule were studied in the cat, in extension rotations and in axial external (ER) and internal (IR) rotations at full extension. Loads were measured in the ligament along the upper edge of the capsule, using mechanically sensitive neurons that were calibrated as load cells. Strains were measured...
Article
Full-text available
These experiments were designed to study the topography of lipid deposition in the stenotic aorta of hypercholesterolemic rats, and to correlate it with flow conditions and intimal stresses and strains studied in a scale biophysical model and in a computer model. A 69% +/- 5% stenosis was produced with a U-shaped metal clip. One month to 8 months l...
Article
Full-text available
A 69 +/- 5% stenosis was produced in the rat aorta, with the purpose of correlating endothelial changes with local flow patterns and with levels of shear stress; the hydrodynamic data were obtained from a scaled-up model of the stenosed aorta. In the throat of the stenosis, where shear stress values were 15-25 times normal, the endothelium was stri...
Article
A finite element based method has been developed for measuring strains in soft tissue. An array of markers is placed on the tissue surface and treated as nodes of a four node isoparametric element. The displacements of the marker centroids are directly measured using a high sensitivity television camera. Finite element method mathematics are then u...
Article
Mechanoreceptive afferents innervating the posterior capsule of the cat knee joint were recorded in a preparation of isolated capsule. The purpose of the experiments was to identify mechanical states in the capsule that were associated with afferent discharge. The capsule was excised from the knee with its bone attachments intact, so that the geome...
Chapter
A method for directly determining strains in soft tissue has been developed. Markers are attached to the tissue to form a grid. The tissue is photographed in the undeformed configuration and then in a series of deformed (loaded) configurations. Using a digitizer, nodal coordinates are entered into a computer from the photographs. A finite element p...
Article
Point source outbreaks of viral hepatitis have been associated with the consumption of contaminated food and water, yet epidemiologic analysis of the disease in the general population usually provides strong correlations with sub-standard socioeconomic conditions. However, statistical analysis of municipal public health records in Worcester, Massac...
Chapter
This chapter describes the responses of joint afferent neurons to loadings of isolated joint capsule. It describes preliminary experiments that were performed in which sections of knee joint capsule, with intact sensory innervation, were excised from the cat knee, and subjected to various loadings in vitro, similar to the experiments described by E...
Article
Worcester, MA, experienced an outbreak of hepatitis during 1969-1970, an expected event which had occurred previously at eight-year intervals since reporting of the disease began in 1950. Other Massachusetts communities of similar character and the nation did not experience an epidemic during that same period. An extensive epidemiologic study of th...
Chapter
The flexural rigidity of four sizes of fourteen different types of sutures were measured using Peirce's ring loop method. The suture materials were ranked according to the lowest value of flexural rigidity. This ranking strongly correlated (r=0.93) with the ranking of handling characteristics obtained thru a survey of practicing surgeons. Thus flex...
Article
Full-text available
BACKGROUND. Skin is a planar tissue that resists loads primarily by reorientation of the collagen fibers. In relaxed skin the collagen fibers exhibit a wavy appearance and are nearly randomly oriented in the plane of the skin. Upon loading, the fibers straighten and reorient in the direction of the load [1]. Prior studies of collagen fiber reorient...

Citations

... Natural vessels are consisted of three layers and the mechanical properties increase from the inner layer to the outer layer (45). A biomimetic scaffold, requires complex materials to provide suitable replacement. ...
... Third, this study paves the way to further specific SD-and DPM-based studies on the universities' third mission and, more generally, on the governance of universities as engines of complex systems of public value co-creation (Cosenz, 2014;El-Jardali, Ataya, & Fadlallah, 2018;Raafat et al., 2013;Skribans, Lektauers, & Merkuryev, 2013). In particular, the adoption of the proposed approach as support for sense-and decision-making both by university managers and by policy-makers could be viewed as a contribution to practice, on the one side, and scientific experimentation of the model's effectiveness and accuracy, on the other side. ...
... Such an integrated approach is named Dynamic Performance Management (DPM) . By adopting a systemic design perspective, this approach has proved to facilitate strategic learning processes in Universities, endowing academic decision-makers with deeper cognitive and informative supports, aptly integrated with the PM systems and characterized by the requirements of relevance, articulation, and selectivity Cosenz, , 2018Zaini et al., 2016;Barnabè, 2003Barnabè, , 2004. A systemic and selective perspective enables to identification and investigation of the main cause-and-effect relations among the forces influencing academic performance into a consistent PM framework. ...
... Design courses form the foundation of many engineering programs, and the engineering curriculum makes heavy use of information sources and technical communication skills [12], [13]. Introducing information and communication skills early in an engineering curriculum, and highlighting these skills through the use of design challenges or solutions, has been demonstrated to have a positive effect on student work [12]. ...
... Furthermore, the hydration change with temperature may also make a contribution. Water plays a significant role in governing the gross properties of skin tissue [195,196], which consist primarily of water. However, due to heating, the level of hydration may vary, e.g., Luescher et al. [197] suggested that primary hydration water is set free during the process of thermal denaturation. ...
... The fibres, when subjected to pressure, straightened and were reorientated, following the direction of the load [13]. Thus, collagen fibres strongly follow the direction of pressure, according to experiments carried out in vivo [14]. In our study the fibres tended to align in the direction of the principal pressure stress exerted on the treated area. ...
... This activity will also train students' independence in learning to grow self-confidence [156,157,158,166,159], is active in learning, discipline and responsibility. Administer information activities will also train students' collaboration skills starting from working collaboratively online [167,168,169], contributing in groups, conveying information clearly [170,171], communicates with each other, cares for all group members [172,173], responds to every group need and participates fully in various steps to solve problems [174,175,176,177]. Activities continued with Role Play activities. ...
... Two major changes were introduced in 2008. First, a formal means of creating student teams was introduced using a company based model that had been recently developed [3]. During the first 2 class periods students interview before the entire class for one of 4 company positions; Chief Executive Officer, Chief Technical Officer, Chief Information Officer and Chief Manufacturing Officer. ...
... A 2013 study showed that 46% of the people ages 21-64 with a disability were employed and a significant number of those were employed part time. These figures compare with an employment rate of 84% for those without a disability[3]. These population demographics clearly indicate that over the next 20 years there will be a rapidly expanding need for assistive devices of all types. ...
... Allen H. Hoffman, et.al [14] In this paper author have discussed about robotic assisted transfer device this device can be used for both stand pivot transfer and fully dependent transfer this device doesn't have user control and tip over stability to include non-level surface. The robot is operated by radio controller which receives the instructions. ...