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Numerical simulations are performed to investigate noise generated by flow in automotive HVAC ducts. A hybrid computational method for analyzing flow noise is applied: Large Eddy Simulation (LES) for predicting flow fields and Multi-domain boundary element method for predicting acoustic propagation. LES gives time-resolved solutions of flow velocity and pressure fields. By applying the acoustic analogy theory, the unsteady flow parameters are translated into sound source in evaluating the acoustic propagation. The computational result shows the noise caused by the HVAC ducts is strong. The noise is of broadband with a peak value at 370Hz. A major contribution of the noise generation is from the center ducts. Two design modifications of the center ducts are explored to regulate the flow structures with the ducts for reducing noise generation. Test results demonstrate the effectiveness of the modifications.

One of the most common barriers to the timely disposition of maintenance discrepancies involves communication difficulties between pilots and technicians. These barriers occur at virtually every operational level of the aviation industry from general aviation to airline. Well intentioned yet incomplete or misdirected communication often results not only in frustration, excessive down time, and recurrence of the problem, but also fosters unhealthy (and inaccurate) stereotypical notions about the overall competence of each group. This paper focuses on a two-phase study designed to identify which human factors impede pilot - mechanic communication and which factors promote pilot - mechanic communication. The project was coordinated by a joint faculty - student research team from the Department of Aviation Technology at Purdue University.

Most airline maintenance human factors training programs miss the mark when it comes to producing optimal behavioral and procedural changes among participating maintenance professionals. While there are many causes for training outcomes which are less than desired and anticipated, principal among these are the failure of most programs to address the pragmatic learning needs of those technicians as adult learners. Attention to andragogical principles such as clear learning goals, readily apparent relevance and direct applicability of material, immediate feedback, learner directed inquiry and self assessment can contribute greatly to achieving optimal results. A program currently under development at Purdue University utilizes a combination of classroom instruction, group discussion, and learner participation in aviation maintenance scenarios as a method for improving human factors education.

In recent years, Nearfield Acoustical Holography (NAH) has been used to identify stationary vehicle exterior noise sources. However that application has usually been limited to individual components. Since powertrain noise sources are hidden within the engine compartment, it is difficult to use NAH to identify those sources and the associated partial field that combine to create the complete exterior noise field of a motor vehicle. Integrated Nearfield Acoustical Holography (INAH) has been developed to address these concerns: it is described here. The procedure entails sensing the sources inside the engine compartment by using an array of reference microphones, and then calculating the associated partial radiation fields by using NAH. In the second part of this paper, the use of farfield arrays is considered. Several array techniques have previously been applied to identify noise sources on moving vehicles.

Financial planners are always anxious to assist engineers and scientists in making retirement decisions. Many engineers, especially Industrial Engineers (IE), have had courses that provide the knowledge to make these retirement financial plans themselves. This paper will provide a method of estimating retirement needs utilizing Excel software and IE college coursework.

Energy budgets for future Controlled Ecological Life-Support Systems (CELSS) must balance not only with respect to primary productivity (i.e., photosynthesis) vs. utilization steps (human maintenance plus preparative and recycling processes), but also with respect to necessary and desired nonlife-support activities of crews (e.g., exploration, research). Present objectives of the NSCORT program at Purdue University include identification of critical paths for biomass conversion to desired forms with energetics and rate-constant properties that are compatible with life-support sustainability within a CELSS. Physico-chemical recycling systems working in conjunction with bioregenerative ones likely will be required to keep time constants of critical processes within reasonable limits.

The renewed interest in electric and hybrid-electric vehicles has been prompted by the drastic rise in oil prices in 2008 and launch of new initiatives by the Federal Government. One of the key issues is to promote the incorporation of electric drivetrain in vehicles at all levels and particularly with emphasis on educational activities to prepare the workforce needed for the near future. Purdue University has been conducting a Grand Prix for over 50 years with Gas-powered Karts. In April 2010, an annual event was initiated to hold an EV Grand Prix where 17 EV Karts participated in the competition. Four of the participating teams comprised of Purdue students in a new graduate course for EV design and fabrication. Using the basic framework of the gas-powered Kart, an electric version was developed as a part of this course. Other participants were also provided with the guidelines and design parameters developed for the course and competition.

The mobility modeling technique is applied to the structure-borne noise path through a vehicle suspension. The model is developed using measured FRF data taken on the isolated components of the suspension and body structure of a midsize sedan. Several important modeling issues of suspensions are resolved. It was determined that multiple degrees of freedom are required to model the coupling at joints between the suspension and body structure. The investigation also demonstrated that bushings should not be included in the measurements used to develop these models and should be added later using simplified bushing parameters. The importance of transfer mobility information between the various suspension attachments was also investigated. The agreement between the mobility model predictions and the measured FRF data for the overall system is better than similar data published in the literature to date.

A finite element model (FEM) of elastic noise control materials like polyurethane foams is presented in this paper, and its implementation in two-dimensional form as a computer program is discussed. So that realistic noise control treatments could be studied, methods for coupling the foam FEM with conventional acoustical and structural finite elements are also described. The validity of the foam FEM is demonstrated by computing the sound absorption and transmission characteristics of simple coupled air/foam/panel systems and by comparing the results with existing experimental and analytical results for such arrangements. The FEM has been used to show that the constraint of a foam layer at its edge stiffens the foam acoustically. In addition, it has been found that the constraint of the ends of the facing panels in a foam-lined double panel system increases the sound transmission loss significantly at low frequencies.

The object of the work reported here was to relate the acoustic intensity level measured near the contact patch of a driven tire on a passenger vehicle with the passby noise levels measured at a sideline microphone during coast and cruise conditions. Based on those measurements it was then possible to estimate the tire noise contribution to the passby level measured when the vehicle under test was accelerating. As part of this testing program, data was collected using five vehicles at fourteen passby sites in the United States: in excess of 800 data sets were obtained.

Acoustic array techniques are presented as alternatives to intensity measurements for source identification in automotive and industrial environments. With an understanding of the advantages and limitations described here for each of the available methods, a technique which is best suited to the application at hand may be selected. The basic theory of array procedures for Nearfield Acoustical Holography, temporal array techniques, and an Inverse Frequency Response Function technique is given. Implementation for various applications is discussed. Experimental evaluation is provided for tire noise identification.

This paper describes sensors and systems developed, or under development, by researchers at Purdue University including: an automated soil nutrient mapping system; a real-time acoustic soil texture sensor; an improved, real-time soil organic matter (SOM) sensor; a real-time soil compaction sensor; and an animal manure application monitoring and control system. Issues to consider for sensor use and development, criteria for evaluating the potential for successful sensor implementation, and likely future sensors for site-specific crop management (SSCM) are also discussed.

Farmers are a small group, mostly college educated who run multi-million dollar yearly operations. Recent favorable economics has allowed this sector to look at new technology and determine the best way to invest in it. New considerations in the last few years have led to minimum/alternative tillage and planting, site specific farming decisions and small technology groups of farmers. The authors have put together their thoughts and wants which should be evaluated by future suppliers of technology and farm machinery.

A feedback controller bas been developed using robust control techniques to control the sound radiated from turbulent flow driven plates. The control design methodology uses frequency domain loop shaping techniques. System uncertainty, sound pressure level reductions, and actuator constraints are included in the design process. For the wind noise problem, weighting factors have been included to distinguish between the importance of modes that radiate sound and those that do not radiate. The wind noise controller has been implemented in the quiet wind tunnel facility at the Ray W. Herrick Laboratories at Purdue University. A multiple-input, multiple-output controller using accelerometer feedback and shaker control was able to achieve control up to 1000 Hz. Sound pressure level reductions of as much as 15 dB were achieved at the frequencies of the plates modes. Overall reductions over the 100-1000 Hz band were approximately 5 dB.

A new laboratory method has been developed to evaluate the acoustical properties of expandable and other automotive sealants. These materials are used to reduce wind, road, and powertrain noise transmission into passenger compartments. In the new method, ASTM E 1050 absorption measurement equipment is used along with a new sample holder, a downstream microphone holder (providing two additional microphone locations) and an anechoic termination. These additions permit measurement of normal incidence transmission loss as well as absorption. It is intended to encourage adoption of this method as a standard way of quantifying the acoustical performance of sealants and sealing composites in automotive noise control applications.

A simple mathematical model was developed and experimentally validated to evaluate how the materials and construction of an automobile tire affect its vibration-radiated noise performance. The mathematical model uses Statistical Energy Analysis (SEA) with modal joint acceptance formulations for wavespeed and radiation efficiency of orthotropically-stiffened and pressurized cylindrical shells. Experimental validation of the model included wavenumber decomposition to determine the dispersion characteristics of an inflated, non-rolling tire in the laboratory. The model is used to conduct a preliminary study into how the various tire constituent materials and construction parameters influence the vibration-radiated noise performance.

Governing equations have been derived to model the space- and frequency-averaged behavior of structural acoustic systems. These equations were derived using assumptions similar to the approximations made in SEA. The equations can be used to develop continuous models of 1-D, 2-D, and 3-D subsystems. The equations have been formulated into a finite element approximation referred to as the Energy Finite Element Method (EFEM). In this paper the theory for coupling plate-like structural systems to acoustical systems is derived and implemented into the EFEM. The results of a verification study using a plate mounted on a rectangular acoustical enclosure are shown for two cases, a mechanically driven plate and an acoustically driven enclosure.

A noise source identification technique for the analysis of thermal systems is presented. The proposed method uses transient spectral sound data to assist in determining the source of sound radiation by tracking the variation of the frequency of tones during transient thermal loading (i.e., thermal system warm-up). By considering the temperature dependence of the modulus of elasticity (Young's modulus) it can be shown that structure related tones will decrease in frequency during warm-up. Tones due to propagation of sound in many fluids (i.e., gases and water) will increase in frequency during warm-up due to the temperature dependence of the speed of sound. The analysis method is demonstrated by identifying the source of several noise tones for a pulse combustion furnace.

The lack of effective and efficient communication between pilots and maintenance technicians has been recognized as a problem in general aviation by both members of the industry and academia. The goal of this paper is to provide an accounting of the impact that communication between maintenance technicians and pilots, or the lack thereof, can have upon both the bottom line and the experience of those who operate within the general aviation arena. The researchers interviewed and observed maintenance technicians and pilots in general aviation operations to identify what members on both sides of the communication process identified as being problematic and troubling. Several of the major barriers to communication, as well as several strategies to overcome those barriers, are discussed.

Purdue University Aviation Technology at West Lafayette and Indianapolis, in concert with a number of industry participants, initiated research at West Lafayette and industry locations on ways and means to address safety concerns affecting a number of air transport carriers as well as general aviation operations. The outcome of the research resulted in a program with airlines and general aviation operators that lead to the development of an interactive instructional technique primarily based on empirical studies at the various facilities. Subsequent to the observation periods were sessions addressing recommendations for resolution of these jointly recognized issues. Part of this effort involved developing innovative methods to report these incidents in a manner that would ensure open, effective communications amongst all the concerned parties. This ongoing research involves the use of students to assess the utilization of current safety resources, or lack thereof, in industry.