Acoustical Characterization of Porous Materials for Automotive Research Paper

Acoustical Characterization of Porous Materials for Automotive Application - Research Paper Example There exists diversity when it comes to porous materials either artificial or natural. Sintered, steel wool, perforated materials and fiber metal are among the porous materials that have been increasingly used in automotive noise control. Following the diversity and variety of porous material characteristics, the study of porous media has proved to be wide and interesting. The review begins with outlining and comparing the models that are intended to be used in predicting the fundamental acoustical characteristics that are applicable in automotive. The paper introduces both the theoretical, empirical and numerical modeling and demonstrates how the models are used to determine the acoustic characteristics of porous materials. The analytical models indicate that the solid constituents of porous material are rigid and the fluid constituents are similar to that of a homogenous isotropic fluid that has been modified. The review also considers the acoustical characterization of porous mate rials and goes further to look at the porous materials modeling while having particular interests on porous materials that are elastic. The fundamental characteristics of porous materials are then illustrated using computational and experimental examples . Introduction In automotive, absorptive materials have various applications in different locations. Absorber pads can serve effectively in several locations such as in the door panel, pillar trim, headliner and bellow the carpet. Porous materials like fibers and foams are normally used in such applications. There acoustic characteristics enable them to serve as absorbers. It is the viscous losses that results in the conversion of energy to heat while sound waves navigate through the fibers or pores that are interconnected in the material. A porous material that is bonded with a barrier that is non-porous conducts the sound energy in waves that are in form of structure-borne. The characteristics which have the desirable influence on this wave form are the structural loss and bulk stiffness (Allard, 1993,p. 56). With reference to automotive applications, absorption is preferred at frequencies that are lower while the weight and thickness are to be limited. Porous materials with air flows resistance that are specific yet different have been identified as to achieve the results that are desired. However, the action of decreasing or increasing the given air flow resistance in order to achieve low frequency results affect high frequency performances. The review thus gives a presentation of a number of different material’s studies which illustrate such behavior. Several models such as the penalization approach demonstrate this behavior by simulating fluids inside and porous regions surrounding the obstacle. Such models are easy to implement and do not need a body fitting or a specific interface treatment. The models are successfully used in the introduction of new passive control methods that entail the imple mentation of a porous layer in between the fluid and the blue-body so as to change the characteristics of the boundary layer. Such a passive control model results in regularization that is drastic especially when it comes to high Reynolds numbers (Allard, 1992, p. 3349). Porous materials come in two phases, namely; the fibrous solid component termed as the frame and the interstitial fluid located in the pores resulting from the frame. Following their low density, porous materials cannot be generally used to make barriers but are commonly applied in the making of materials that absorb

Writing process Essay Example | Topics and Well Written Essays - 750 words

Writing process - Essay Example The students can browse through books, journals and website to find adequate knowledge as well as possible options for the topic. The student may come up with five possible topics which is still subject for making it more specific and narrow so that paper will have focus and central theme.Topic formation is part of this stage wherein the student has decided for the main topic, thesis statement or central theme for the paper. The topic sentence or thesis statement must be formulated. Student may also use free writing to take down his own thoughts, ideas and reactions about the topic.Importance: This stage is important for this enhances the students' ability to come up with their stored knowledge and practice their creative minds with regards to writing. Aside from this, this will also develop decision-making skills for the student will be the one to discern the topic which best interests them and which they know most about. It is necessary for the student will be able to gauge how muc h he knows the topic and how much interest he has on his chosen topic. Aside from coming up with the topic, an outline can also be produced.Drafting involves the transfer of ideas from the pre writing section to a formal draft. Since the outline has been made from the pre writing section, it is time for the student to arrange and structure his argument as well as all the information he has researched. The introduction as well as the conclusion is formulated at this stage. Citing the references involves the use of writing styles such as Harvard style, MLA, APA or Chicago methods. The note cards that were used during the pre writing section will be of great help here for it has all the details regarding the publications and materials that were used for the draft of the paper. The student should check if their instructor specified the paper format or it is up to them to decide which they find appropriate. The in-text citations can be properly placed in the draft and again, the note cards will be very helpful at this time. Importance: The ability to organize all the gathered information into a structured, informative and well-written paper will be improved and makes this stage essential. Plagiarism is taboo when it comes to writing. The best way to teach students how to prevent this from happening is for them to learn how to paraphrase and use writing styles (APA, MLA, etc.) as well as in-text citations. Editing Editing includes rereading the draft means to check on any grammatical errors, spelling errors, citation omissions, effectiveness of the sentences, use of transitions, punctuations and paragraph structure as well as to review if the paper is organized in such a way that it is readable, understandable and progressive. It is also necessary to check if there are any content problems and rhetorical issues. Revising involves making the necessary changes after proofreading. Importance: These stages are essential to ensure the good quality and effectiveness of the paper. Feedback is necessary from the instructor to inform that student how the paper appeals to readers. Revising Revising includes making decisions abouthow the student wantstoimprovehis writing, looking at one's writing from a different point of view, picking places where one's writing could be clearer, more interesting, more informative and more convincing. It is