Acentech Inc.

Cambridge, MA, United States

Acentech Inc.

Cambridge, MA, United States
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Ungar E.E.,Acentech Inc.
Sound and Vibration | Year: 2010

Some suggestions for predicting the traffic related vibrations in a candidate building design that exists only in the form of drawings are discussed. A site's vibration propagation characteristics may be expected to depend not only on the local soil's constituents and layering, but also on the soil's moisture content and temperature. If a building is supported on columns that rest on discrete footings, it may perhaps suffice to consider each footing to act at a single point and to address the motion of that point in terms of six-component impedance matrices. However, in order to determine the motions of the building's floors one needs to account for the totality of the motions transmitted to the floors through all of the columns, so that one needs to consider the different magnitudes and phases of the soil motions that act at the column bases. All analytical modeling, and particularly statistical energy analysis (SEA) modeling, is better suited to predicting the effects of structural modifications than to predicting absolute vibration response magnitudes.

Fullerton J.L.,Acentech Inc.
24th National Conference on Noise Control Engineering 2010, Noise-Con 10, Held Jointly with the 159th Meeting of the Acoustical Society of America | Year: 2010

The installation of a geothermal heat pump in the basement of a 1900 era home introduced significant noise and vibration to a bedroom above, which was discussed in detail in a previous conference. After mitigating the noise and vibration using piping isolation products, lower levels of noise and vibration still remained. This paper will discuss pursuits that were implemented and the very effective resolution for mitigating the noise and vibration that was generated by the heat pump.

Tray Edmonds P.E.,Acentech Inc | Fullerton J.L.,Southeastern Elevator Consulting LLC
INTER-NOISE 2015 - 44th International Congress and Exposition on Noise Control Engineering | Year: 2015

A majority of traction elevators for mid-rise and high-rise buildings are configured with the hoist equipment directly above the elevator shaft where the associated cab and counterweight are located. A recent noise control project in a residential tower involved an alternate elevator system design, which included an offset configuration of the hoist equipment from the elevator shaft. This offset configuration allowed for the equipment to be placed at a lower height. This design had the benefit of allowing an additional occupied floor in the building. However, this reconfiguration of the hoist equipment resulted in several unique noise and vibration control challenges. The unique features of this offset hoist equipment design and the resulting noise and vibration control approaches for this residential building are discussed in the following paper. © 2015 by ASME.

Harris A.S.,University of Manchester | Wood E.W.,Acentech Inc.
41st International Congress and Exposition on Noise Control Engineering 2012, INTER-NOISE 2012 | Year: 2012

A tribe with elders and villagers; a university with professors and students; a studio with a master and protégés - all are mentoring environments. Bolt Beranek and Newman Inc. (BBN), founded to provide consulting services in acoustics, became a mentoring environment in acoustics. For more than a decade the authors worked together at BBN. It was an exciting time in acoustics and at BBN. The National Environmental Protection Act (effective 1970 January 1) and the Noise Control Act (1972), and the growth and decline of the EPA's Noise Office set the stage for major environmental activity. This period also coincided with major architectural acoustics projects - performing arts centers throughout the world, for example. BBN's senior staff included leaders in all of these fields. The authors benefitted from the mentoring environment at BBN and the willingness of senior staff in all disciplines to share their knowledge and wisdom. Subsequently, the authors went on to help found firms that use the same model. In this paper, they offer their experiences at BBN and later as a catalyst for discussion of mentoring in this session.

Sanayei M.,Tufts University | Kayiparambil P.A.,Tufts University | Moore J.A.,Acentech Inc. | Brett C.R.,Simpson Gumpertz and Heger
Engineering Structures | Year: 2014

Buildings located close to transportation corridors experience structure-borne sound and vibration due to passing traffic which can be disruptive to operation of sensitive equipment in manufacturing, and medical facilities. Structure-borne sound and vibrations, when high may also be annoying to human occupants in residential, office, and commercial buildings. Hence, there is a growing need for cost effective sound and vibration predictions to evaluate the need for mitigation.The research focuses on in-situ testing of a full-scale building for verification of a previously developed impedance-based methodology and to create a prediction model to study ground-borne vibrations in the test building. A mitigation methodology was also examined using the verified prediction model.Impedance modeling involves the propagation of axial waves through columns combined with the impedance of the intermediate floor slabs. The vibration transmission in the building was characterized and predicted using a single column model with attached floors.Train-induced floor vibrations in an existing four-story building in Boston were measured and compared with predictions of the impedance model. The impedance model predictions closely matched with the measured floor responses.A previously suggested mitigation method was investigated analytically using the impedance model. A thickened floor referred as the "blocking floor" was used on the lower elevation of the building and the reduction in vibration at the upper floors of the building was compared for various thicknesses of the blocking floor, to study its efficiency. The blocking floor has high impedance and reflects a major portion of the vibration transmitting in the columns preventing it from reaching the upper floors. The blocking floor was found to mitigate the transmission of ground-borne vibrations to upper floors. © 2014 Elsevier Ltd.

Nugent R.E.,Acentech Inc. | Zapfe J.A.,Acentech Inc.
Sound and Vibration | Year: 2012

Considerations for new buildings near rail lines, how the vibrations from rail systems are affected by the presence of the building and what additional steps can be taken to provide enhanced mitigation, are discussed with the help of case studies. These considerations include field vibration measurements to force-plate signal data acquisition, analysis and reporting, with data export capabilities into raw signal, signal graph and parameter value formats. In designing supplemental vibration mitigation, one must always be mindful of the fact that most pieces of sensitive equipment have their own internal isolation systems. Stability issues can arise if one soft spring is simply stacked on top of another soft spring without a large intermediate mass between the two isolation systems. The intermediate mass, commonly referred to as an inertia block, serves to dynamically separate the two isolation systems which means they can effectively be treated as two dynamically independent isolation systems.

Sanayei M.,Tufts University | Zhao N.,Tufts University | Zhao N.,China Sinogy Electrical Engineering Co. | Maurya P.,Tufts University | And 3 more authors.
Journal of Structural Engineering (United States) | Year: 2012

Buildings that are located near transportation corridors often experience floor vibrations induced by passing trains or traffic, which causes building owners some concern. In this paper, a mathematical, impedance-based (wave propagation) model is presented for predicting train-induced floor vibrations in buildings. The model analytically predicts velocities, velocity ratios, and impedances. The analytical predictions of the model were compared and validated with the measured floor vibrations in a 4-story scale model building constructed by the writers. These predictions closely mimicked the measured responses. Using the results from the method presented indicate that the vibrations on the upper floors can be mitigated by increasing the thickness of a floor at a lower level in the building. This lower-level floor with the increased thickness is called a blocking floor. The scale model building was tested with and without a blocking floor. The predicted and measured responses of the scale model building using floor slabs with various thicknesses on the first floor are compared. It is concluded that the use of a blocking floor can mitigate the transmission of structure-borne vibration to the upper floors. © 2012 American Society of Civil Engineers.

Fullerton J.L.,Acentech Inc.
42nd International Congress and Exposition on Noise Control Engineering 2013, INTER-NOISE 2013: Noise Control for Quality of Life | Year: 2013

Teaching acoustics to architecture students is an enlightening position in which to find oneself; teaching acoustics to architecture students within a course period of only 12 Hrs requires a balance of clear organization, concise and efficient delivery, student engagement and the instructor's ability to adapt. Having taught in this format for several years, experience has shown that organization and efficiency are critical for delivering the conceptual content of architectural acoustics within this short period. Short lists punctuate the key concepts and topics and provide a framework for the students to establish their own organization of the new knowledge. Equally important are engaging the students to require them to think about and apply what they are learning; class participation and a final project, which will be discussed, provide these opportunities. The final important ingredient for success is the instructor's ability to listen and understand the questions from the students; clarifying confusion and decoding different terminology, injecting relevant experiences and insights, and using analogies and anecdotes all reinforce the learning process. While this short course length is not advisable or desirable, the approaches discussed help make the time most effective for the students' ability to succeed at being more aware of acoustics.

Azevedo M.,Acentech Inc.
Proceedings of Meetings on Acoustics | Year: 2013

Auralization has become a valuable tool to explore the acoustics of spaces and activities that no longer exist. Generally, acoustical archaeology has explored a fairly limited number of sources in a space to determine specific acoustical aspects of the sound of the spaces and to separate intentionally designed acoustical phenomena from the often unintended effects of the architecture. We have expanded this technique to recreate the entire soundscape of a specific event, in this case John Donne's 1622 Gunpowder Plot sermon at Paul's Cross, outside St. Paul's Cathedral in London as it was prior to the fire of 1666. This work augments ambisonic auralization techniques with techniques borrowed from computer-aided music composition and audio production to create an immersive acoustical environment for the purpose of exploring the experience of listeners at many positions in a crowd that can be varied in size in real time. The paper outlines the role of geometric acoustics modeling, realtime convolution, randomized and statistically-derived sound event triggers, and other techniques employed to auralize a soundscape that includes the sermon, crowd response, and the ambient sounds of pre-Industrial London. © 2013 Acoustical Society of America.

Sanayei M.,Tufts University | Maurya P.,Tufts University | Moore J.A.,Acentech Inc.
Engineering Structures | Year: 2013

Buildings located near surface trains and subways are subjected to surface train and subway-induced vibrations. Cutting edge technologies in laboratories and precision manufacturing facilities often include operation of vibration sensitive equipment. Human comfort in the form of feelable vibrations and audible noise in residential and office buildings is also a concern. It is thus imperative to reduce these vibrations inside buildings to acceptable levels with the design of an efficient vibration mitigation system. Incorporation of a vibration mitigation system in a building in design phase requires prior understanding and characterization of subway and surface train-induced base excitations of buildings before and after the construction of a structure to meet serviceability criteria.The vibrations measured at the foundation slab of buildings serve as the base excitation for the building and transmit to the to upper floor levels through columns. The focus of this paper is to quantify the amplitudes and frequency contents of vibration level measured at foundation slab and compare these vibration measurements inside the building at foundation level with the open field measurements. In this context, an exploration of ground-borne vibration characteristics was performed at six sites in the Boston area. Three sites were selected for measuring train-induced vibration and another three were considered for subway-induced vibration study. Vibration measurements were performed on the building foundation slab as well as in open fields adjacent to the building. These vibration measurements were quantified and compared. It was found that in the case of surface train-induced building vibrations, open field vibration levels can be conservatively used in the design of buildings. However due to inconsistency in observations, a similar conclusion was not drawn for the case of subway-induced building vibration. This paper also provides the bases that would allow the designer to estimate the vibration levels in sensitive locations within the building. These estimated levels determine the extent to which mitigation is required to meet vibration criteria. © 2013 Elsevier Ltd.

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