Indri Yaningsih

Sebelas Maret University | UNS · Department of Mechanical Engineering

This study presents a numerical investigation of bullet impact on sandwich panel structures. This research aims to demonstrate the ideal performance of sandwich panel structures in resisting ballistic loads based on the type of core geometry and materials used. Numerical simulations were conducted using the Johnson–Cook material model and applied i...

Transportation is vital due to its capability to transport cargo and people massively. However, if maritime accidents take place, they may cause a significant impact not only on the economy and lives lost but also on the environment. This review paper provides a summary of research and reports on marine accidents, including the inclusion of ship ty...

Over the past few years, marine transportation accidents have decreased significantly. Marine transportation accidents are complex events often caused by multiple factors through the interaction of multiple parties. These accidents can cause loss of human life and property and ecological and environmental damage. They could disrupt the balance of t...

This study not only explores the fabrication of rare zeolites from waste pumice and examines the impact of aging on their porosity and adsorbate uptake but also provides practical insights for waste management and agricultural applications. The use of organic templates was avoided in the synthesis due to their high cost and pollution associated wit...

Buku monografi yang berjudul Teknologi Termal Matahari (Solar Thermal Technology) ini mencakup berbagai pokok pembahasan mengenai energi panas matahari baik secara teoritis maupun praktis. Tidak dapat kami bantah bahwa energi matahari tidak dapat terpisahkan dari kehidupan sehari-hari manusia. Mulai dari yang paling awam pada aplikasi pengeringan p...

Light trapping is a popular method used to improve the performance of photothermal absorbers. Granular structures are one of the light-trapping structures currently developed. In this paper, a review on the working principle and types of granular structures is presented. Furthermore, recent findings pertaining to the innovations of granular structu...

The collector and absorber are the two main components most influential in obtaining high solar thermal performance. This study used a 30 × 30 cm Fresnel lens under a xenon lamp to improve the temperature generation performance. The materials photothermal absorbers used are coal, andesite, and pumice, with an average granular structure diameter of...

This study presents a comprehensive analysis using the finite element method (FEM) to examine and evaluate the behavior of fuel carrier ship structure. Sandwich panels are effective structures for use in ship structures due to their lightweight yet robust nature. Sandwich panels used in ship structures have various core shapes, such as hexagonal, c...

In this study, the ultimate strength of a stiffened panel, which is one of the important components of ship structure, was analyzed by considering the effects of initial imperfection and geometric aspects with variations of random amplitude. The initial imperfection is influenced by local, torsional, and column imperfection modes, while the span/ba...

Carbon-fiber-reinforced polymers (CFRPs) are a composite material popular for thin-walled structure applications because of their advantages over other materials. In this study, numerical simulation analysis based on the finite-element method to identify the tensile behavior of CFRP woven material has been carried out. The method used has been veri...

The development of cost-effective and environmentally friendly solar thermal technologies that deliver high performance poses several challenges, where the collector and absorber components play a pivotal role. This research addresses these issues by investigating enhanced temperature generation using a 30 cm × 30 cm Fresnel lens collector under so...

This research aimed to determine the thermal characteristics of sengon wood due to drying at temperature of 70, 80, and 90oC with air velocity of 1 and 3 m/s using infrared (IR) and combined infrared-hot air (IR-HA) method. The thermal characteristics analyzed included temperature distribution, reduction in moisture content, and drying rate. The re...

Ethanol mixed with a primary fuel is a promising alternative fuel. To increase performance, an optimal compression ratio must be set. The compression ratio is the ratio of the maximum volume divided by the minimum volume. Ethanol-gasoline mixtures have high octane and can be used in high-compression engines. This research aims to identify how chang...

The viability of renewable energy sources (emphasizing solar energy) helps reduce the barrier of fossil energy depletion. Despite the issue of low thermal performance, different techniques are projected to gain high energy to boost the heat transfer for the solar energy system. This experimental work evaluates the thermal performance enhancement of...

Dams’ systems were constructed to create higher water levels as high as head for generating renewable power. However, the construction process has impacted environmental changes such as land dredging and displacement of population settlements. Therefore, using a micro hydro power plant is the one of the solutions because this power plant is environ...

The utilization of RD-type silica gel material as an adsorbent within the Personal Protective Equipment (PPE) layer underwent a comprehensive analysis aimed at elucidating its unique adsorption characteristics through the application of MATLAB programming. This study aims to determine the characteristics of silica gel RD to water vapor in terms of...

p>Pariwisata adalah salah satu faktor pendorong ekonomi di sebuah daerah. Perkembangan sektor pariwisata suatu daerah dapat memacu pembangunan sarana infrastruktur yang lain, seperti hotel, minimarket, jalan raya dan lain-lain. Dengan mengembangkan sektor pariwisata, maka akan terciptanya lapangan pekerjaan yang baru dan mengurangi pengangguran. Sa...

The use of technology in everyday life is unavoidable, considering that technological advancement occurs very quickly. The current era is also known as industry 4.0. In the industry 4.0 era, there is a convergence between the industrial world and information technology. The use of modern machines in the industry makes it possible for business actor...

A fast patrol boat is one of the ships intended to defend a region and rescue and search in the accident event so that the ship must have a high level of security and survivability performances. This study uses 9 design variations with various main dimensions and hull lengths to determine the effect of the different main dimensions on the hydrodyna...

The world's oil and gas sectors are diverse. They utilize offshore pipes to generate millions of barrels of oil and gas to meet global energy demands. In this study we identified the critical buckling load that occurred on a cylinder shell (also known as radial buckling). Offshore pipe design must meet several criteria, one of which is the requirem...

Thickness checking is one of the quality control procedures in the brake pad industry. This research aims to address the issue of the time effectiveness of the thickness checking by turning the technique into an automatic process, from specimen preparation to data recordings; the technical aspects, the geometric design, and the structure analysis a...

Heat and mass transfer characteristics (HMTCs), which defined the latent and sensible load, are essential for developing an effective desiccant dehumidification system (DSDHS). Therefore, the current work provides an investigation on the HMTCs, in the form of the Nusselt and Sherwood numbers. Under constant adsorption temperature of 293 K, the HMTC...

The study aims to achieve energy savings of air conditioning systems using desiccant dehumidification with low-cost adsorbent. For this purpose, two existing activated carbons were evaluated in terms of water adsorption capacity. The theoretical calculation of effective adsorption from the water adsorption isotherms revealed that the studied activa...

This research investigated two-phase heat transfer numerically using TiO 2 /water nanofluids to enhance the thermal performance in a flat tube car radiator. Nanofluid is a colloid dispersion in a nano-sized which is a breakthrough in terms of the thermal devices. The radiator is widely used in the automotive industry as a heat exchanger. The enhanc...

In order to enhance the heat transfer performance of heat tubes, porous media are often sintered into them. This increases the heat transfer area due to the surface area being increased by the porous media. Our The test apparatus consisted of a double tube structure, and the length was 150 mm. Previous experiments have shown its usefulness and reve...

After publishing an article in which the impact of wing-width ratio of double-sided delta-wing tape (T-W) inserts on thermal-hydraulic performance [Wijayanta et al., Appl. Therm. Eng. 145 (2018) 27–37] were investigated, we have extended our work to modified enhanced heat transfer area design for wing-pitch ratio (P/W) acting on the geometric featu...

Demands of standalone dehumidification systems have been increasing in order to realize energy savings in air-conditioning processes. In a desiccant dehumidification system, the water vapor from the moist air undergoes a phase change phenomenon, this being from vapor to adsorbed phase, a process analogous to latent heat exchange. The energy exchang...

This paper provides an analysis of the adsorption kinetics by using image processing algorithm. Rapid adsorption kinetics is increasingly important because it offers a good mass transfer hence improves the efficiency of the sorption system. For adsorption kinetics, it is required to determine the first stage of the measurement precisely. Therefore,...

Controlling the temperature and humidity is important to achieve a comfortable space for occupants. Numerous studies have shown that the desiccant air conditioning system offered great potential to solve this problem. However, to guaranty the continuous working of the system, desiccant air conditioning is required a regeneration process which alway...

Effect of slant angle (α) of louvered strip insert on single-phase forced convection heat transfer and friction factor of internal flow was investigated experimentally. The parameter of slant angles (α) 15°, 20° and 25° was examined at the Reynolds number (Re) of 5300–17,500. The plain tube was also performed for comparison. The results show that t...

One of the challenges in the development of heat exchangers is to minimize their energy consumption. This can be achieved by enhancing the heat transfer rate, which will boost the thermal performance of heat exchangers. Delta-wing vortex generators fitted in a double-pipe heat exchanger will generate vortices with more intermixing of the flowing fl...

Adjusting the heat and moisture of a conditioned space is important to maintain the comfort of the air. Adding or removing heat and moisture depends mainly on the heat and mass transfer characteristics within the system. In this study, the heat and mass transfer characteristics, in the form of the Nusselt number (Nu) and the Sherwood number (Sh), o...

Enhanced tube by employing double-sided delta wing vortex generator with alternate axes (DW-AA) was investigated to observe thermal-hydraulic performance in the form of Nusselt number (Nu) and friction factor (f). DW-AA was examined for a given wing-width ratio (wr) of 0.47 and 0.63 with varied Reynolds number (Re) of 5,300 up to 14,500. A sophisti...

The effect of adsorption temperature (20ºC; 25ºC) and switching time for adsorption and desorption processes of 60:60 min, 60:90 min, 60:120 min was experimentally investigated on adsorption dehumidification system. It was performed to examine the performance index and moisture adsorbed ability. We found that performance index and moisture adsorbed...

Adsorption dehumidification is gained extensive consideration as an alternative for air conditioning devices. Choosing the appropriate parameters is necessary to improve the performance of the system. In this study, we performed the impact of desorption air temperature on the desiccant ability and thermal performance of desiccant dehumidification (...

The current research highlights the potential of using desiccant dehumidification technology with the merits of low initial energy consumptions. The system consists of desiccant (DSC) block units, dehumidification and regeneration air sources, air flow control valves, and a set of the heat exchanger. Attention was given to the DSC blocks. The block...

Penelitian ini bertujuan untuk mengetahui pengaruh jenis proses pemotongan pada mesin penggilingan terhadap getaran dan kekasaran permukaan aluminium 6061. Spesimen dibuat dengan menggunakan tipe pemotongan face milling, profile milling, pocket milling, slot milling dan pengeboran.. Pengambilan data kekasaran permukaan dilakukan pada semua jenis pr...

Penelitian ini dilakukan untuk mengetahui pengaruh penerapan CAD /CAM terhadap proses penggilingan CNC terhadap kekasaran dan ketelitianpermukaan. Spesimen dibuat dengan menggunakan tujuh jenis prosespemotongan. Terdapat face milling, pocket milling, profile milling, slotmilling, pengeboran, thread milling dan surface contouring. Hasil penelitianme...

Turbulator is recognized as a method to increase the performance of the heat exchanger. Turbulator in the form of V-cut twisted tape insert could help to increase the performance by enhancing the coefficient of the heat transfer. This paper proposes a new design of V-cut twisted tape insert (VTT) with different width ratio (w/W), which investigated...

The impact of double-sided delta-winglet tape (DWTs) inserts on convective heat transfer and friction behaviors in a tube was experimentally investigated. Three DWTs with ratios of winglet-height (b) to inner tube diameter (di) called blockage ratio (Rb) of 0.28, 0.35 and 0.42 were tested and their performance was compared to that of a longitudinal...

Helical screw-tape insert has been proposed to improve the heat transfer coefficient of single-phase flow concentric tube heat exchanger. Helical screw insert is manufactured by twisting homogeneously a zinc strip of 0.25 mm thick over a 2.2 mm rod. Two different twist ratio (Y) of 2.5 and 4.1 have been introduced to investigate the heat transfer a...

Vibration that occur in machining process is forced vibration. This vibration caused by external force excitation. External force that cause vibration in machining process is cutting force. This research was aims to determine the effect of cutting fluids and cutting speeds to vibration in milling process. The specimens were made using a cutting pro...

p>Bergles, A.E., 1985, Techniques to Augment Heat Transfer. In:Rohsenow, W.M., Hartnett, J.P.,Ganie, E. (Eds.), Handbook of Heat Transfer Application, McGraw-Hill, New York. Cengel, Y.A., Cimbala, J.M., 2006, Fluid Mechanics: Fundamental and Applications, 1st edition, McGraw–Hill, New York Holman, J.P., 2010, Heat Transfer, 10th ed., McGraw–Hill,...

The impact of blockage ratio (Rb) on convective heat transfer and friction behaviors in a tube equipped with the double-sided delta-winglet tape insert (DWTs) was investigated experimentally. Two blockage ratio (Rb = 0.28 and 0.35) were proposed in this study. The effect of parameters was compared with the result of longitudinal strip (L-S) and pla...

There are many factor affecting the quality of product that are produced from milling machine process. The quality is mostly about surface roughness and precision. Those affecting factors are the selection of cutting parameter and use of cutting fluid. The research is done in order to know the effect of using cutting fluid and feed rate to aluminum...

The effects of twisted tapes using various wings with alternate axes on heat transfer, flow friction and thermal performance characteristics in a concentric tube heat exchanger are experimentally investigated. The influence of wing shape including triangle, rectangle and trapezoid are also studied. The experiments are performed using twisted tape w...

The effects of pitch-length louvered strip inserts with a forward arrangement on heat transfer and friction factor characteristics in a concentric pipe heat exchanger were experimentally investigated. Louvered strip insert was installed inside the tube. For comparison, the experiment without louvered strip (plain tube) was conducted. All cases were...

Penelitian dilakukan untuk menguji karakteristik perpindahan panas dan faktor gesekan pada penukar kalor pipa konsentrik dengan trapezoidal cut twisted tape insert. Seksi uji adalah penukar kalor pipa konsentrik satu laluan dengan pipa dalam dan pipa luar terbuat dari aluminium. Dimensi pipa dalam; diameter luar 15,84 mm dan diameter dalam 14,34 mm...

In this paper, an experimental study on the effect of angle attack in V-down continuous ribs on heat transfer and friction factor in an artificially roughened air heater duct is presented. The electric heater with a constant heat flux as a simulation of the indoor testing solar air heater is used to heat the roughened part of rectangular duct while...

In this study, an experimental investigation has been carried out for heat transfer and pressure drop characteristics of a concentric double pipe heat exchanger using the perforated twisted (PT) tape inserts with various axial pitch ratios. The experiments were performed using PT tape inserts with tape-twist ratio of 3.97 and the three axial pitch...

Heat transfer, flow friction and thermal performance factor characteristics in a concentric pipe heat exchanger fitted perforated twisted tape insert with parallel wings (PTPW), using water as working fluid are investigated experimentally. The design of PTPW involves the following concepts: (1) wings induce an extra turbulence near tube wall and th...

This research examined the effect of the use of spray humidifier and pad humidifier on the productivity of a desalination unit based heat pump with using humidification and dehumidification process. In spray humidifier there were 5 pieces of sprinklers for spraying sea water. In pad humidifier, sea water was distributed evenly over the top by means...

Pengaruh modifikasi sisipan pita terpilin terhadap karakteristik perpindahan panas, faktor gesekan dan unjuk kerja termal di pipa dalam dari penukar kalor pipa konsentrik telah diteliti. Penelitian dilakukan dengan menggunakan tiga modifikasi sisipan pita terpilin yang berbeda, yaitu perforated, notched dan jagged twisted tape insert. Classic twist...

Abstract : This research was carried out to investigate the single phase flow characteristics of upward flow with/without heat exchange in narrow annulus of concentric tube heat exchanger. In this experiment, direction of flow was upward flow. Hydraulic diameter of the narrow annulus was 4.77 mm. Flows in the inner tube and in narrow annulus were i...