A method is presented for vibro-acoustic analysis of elastically restrained orthotropic shear deformable plates subjected to excitation forces at different locations. The vibration of the shear deformable plate is formulated on the basis of the Ritz method and a simple first-order shear deformation theory in which 4 rather than 5 displacement components are used to simulate the deformation of the plate. The accuracy of the modal characteristics (natural frequency and mode shape) of an orthotropic plate predicted using the proposed method is verified by those obtained using other methods. The vibration responses of the plate are used in the first Rayleigh integral to construct the sound pressure level (SPL) curves of the plate subjected to excitation forces at different locations. The suitability of the present method for sound radiation analysis is validated by comparing the SPL curve obtained using the present method with those obtained using the other methods. The effects of different system parameters on the SPL curve of the plate are studied by means of several numerical examples. It has been shown that excitation location has significant effects on the smoothness of the SPL curve.

The specimens were prepared with polyester polymer reinforced with natural fiber from three types of bamboo, namely Gigantochloa Apus, Bambusa vulgaris, and Bambusa blumeana. Their tensile properties were compared and investigated. In this paper, the specimen utilization of hand-wet layup processes of polyester resin with natural fibers. The fibers were treated with 5% NaOH solution to remove hemicellulose and create better debonding between matrix and fiber. Bamboo-reinforced composite of 3 types of bamboo with fractions 60% volume is thorn bamboo, Bambusa vulgaris, Gigantochloa Apus, and bamboo wipe without alkali. Of the three types of bamboo, the highest tensile strength of Gigantochloa Apus was soaked using NaOH with an average value of 37.06 MPa, with a tensile strain of 4.11%. In contrast, the lowest tensile strength value is Gigantochloa Apus which was not immersed in NaOH with an average of 13.79 MPa, a tensile strain of 2.54%. This matter shows the effect of immersion on tensile strength bamboo fiber composite. The results of the tensile strength of each type of bamboo obtained in this research, among others, bamboo thorn's tensile strength of 22.81 MPa, Bambusa vulgaris tensile strength of 16.69 MPa, bamboo apus 37.06 MPa, and Gigantochloa Apus without alkali 13.79 MPa. The observations show that Gigantochloa Apuscomposites are suitable for use as alternative tensile materials.

A new vibro-acoustic method is presented to analyze the sound radiation behavior of orthotropic panel-form sound radiators using strip-type exciters to exert line loads to the panels for sound radiation. The simple first-order shear deformation theory together with the Ritz method is used to formulate the proposed method that makes the vibro-acoustic analysis of elastically restrained stiffened orthotropic plates more computationally efficient than the methods formulated on the basis of the other shear deformation theories. An elastically restrained orthotropic plate consisting of two parallel strip-type exciters was tested to measure the experimental sound pressure level curve for validating the effectiveness and accuracy of the proposed method. The resonance characteristics (natural frequency and mode shape) detrimental to sound radiation are identified in the vibro-acoustic analysis of the orthotropic plate. For any orthotropic sound radiation plate, based on the detrimental mode shapes, a practical procedure is presented to design the line load locations on the plate to suppress the major sound pressure level dips for enhancing the smoothness of the plate sound pressure level curve. For illustration, the sound radiation enhancement of orthotropic plates with different fiber orientations for aspect ratios equal to 3, 2, and 1 subjected to one or two line loads is conducted using the proposed procedure. The results for the cases with two line loads perpendicular to the fiber direction and located at the nodal lines of the major detrimental mode shape may find applications in designing orthotropic panel-form speakers with relatively smooth sound pressure level curves.

The existence of the Company PT. Pupuk Iskandar Muda in Dewantara District, North Aceh Regency, Aceh Province, in addition to having a positive impact, also harms the environment name in the form of air pollution (ammonia gas leakage), which is surrounding community. It hoped that the air pollution could control the North Aceh Regency Government and the Company not to harm the surrounding community. However, in reality, the Regional Government has not been able to carry out air pollution control/mitigation properly. In its prevention efforts, the Company has not fully protected so that the incidence of pollution repeats itself from year to year without special handling. This phenomenon seems to be commonplace and is considered trivial by the Company, the government and the surrounding community. The smell of ammonia gas that occurs almost every day in the Dewantara District is natural. All stakeholders are not dangerous and can coexist with it. It should not be left alone, let alone decided by academics as a harmless problem. The implementation of this research uses a descriptive-analytical study wherein obtaining as much data as possible is carried out through various techniques that are arranged systematically to seek data collection from research results that follow the nature of the problem and the research objectives to obtain. This study aims to determine the extent to which the implementation of air pollution control/mitigation (ammonia gas) and to find out what obstacles are experienced by local governments and companies in carrying out control/mitigation of air pollution (ammonia gas) as a result of the operation of PT. Pupuk Iskandar Muda in Dewantara District, North Aceh Regency, Aceh Province. This research hopes that strategic steps can be taken by the Regional Government and the Company so that the chronic air pollution (ammonia gas) will be immediately resolved and will not happen again. The outputs of this research are research reports and scientific publications in accredited national journals and research books with ISBN.

This article presents the results of investigations on composite materials reinforced with natural fibers from bamboo trees with variations in fiber direction. Because of the promising potential of the bamboo plant where its availability is abundant and sustainable, research on the mechanical properties of bamboo fiber is still very interesting to do to gain the maximum of it potential. Bamboo fiber is extracted from bamboo stems by beating.  Treatment with soaking in 5% alkaline for 120 minutes was carried out before the specimen was made using an epoxy resin matrix. The process of making composite materials is carried out using the resin infusion method. Composition Specimens were prepared with a volume fraction of 40% and 60% for resin and fiber, respectively. And variations in fiber direction are set at 30, 45, and 60 degrees. The characteristics of the mechanical properties were obtained by testing the dance using a universal testing machine, while the bond characteristics between the matrix and the fibers were observed through micro-observation using the SEM tool. The specimen in a fiber orientation of 30° performs the strongest tensile strength of 165.9 MPa.