Erosion of metals by multiple impacts with water

Investigation determines - relation between impact velocity and minimum number of impacts producing visible erosion, relation between high frequency fatigue stresses and number of cycles to failure, water-hammer stresses relation to high frequency endurance limit, erosion rate as exposure time function, and correlates experimental data with recent theory

Experimental and analytical investigations on multiple liquid impact erosion

Experimental and analytical studies of multiple liquid impact erosion of aluminum and stainless stee

Cavitation damage in liquid metals /potassium studies/ Technical progress report, 1 Aug. - 31 Oct. 1966

Cavitation damage resistance of refractory alloys in high temperature liquid potassiu

Pergerakan Jalan Stabil Robot Hexapod di Atas Medan yang Tidak Rata

Beberapa tahun terakhir, bencana alam seperti gunung meletus, tanah longsor, dan banjir sering terjadi dan menimbulkan korban jiwa. Upaya penyelamatan korban jiwa dalam bencana tersebut menjadi sulit dilakukan, karena daerah bencana sangat sulit dicapai oleh tim penyelamat. Permukaan tanah daerah bencana yang tidak rata dan potensi bencana susulan menjadi salah satu kendala dalam penyelamatan korban oleh tim penyelamat. Proses penyelamatan korban biasa dilakukan oleh tim penyelamat dengan membawa mobil ambulans ke lokasi bencana dan tim penyelamat menyusuri daerah bencana untuk menemukan korban. Masalah yang akan muncul adalah tim penyelamat saat mencari korban membahayakan diri saat berada di daerah bencana yang masih berpotensi mengalami bencana susulan, mobil ambulans untuk mengangkut korban tidak bisa menuju lokasi korban karena permukaan tanah daerah bencana yang tidak rata. bila korban berada jauh dari lokasi mobil ambulans, tim penyelamat akan membutuhkan waktu untuk membawa korban menuju mobil ambulans. Sehubungan dengan ini diusulkan suatu rancangan pemecahan masalah dengan menggunakan teknologi robot. Robot digunakan untuk melewati daerah yang memiliki permukaan yang tidak rata berupa sebuah prototype robot hexapod yang menerapkan inverse kinematic dan algoritma gait, sehingga robot dapat melewati daerah yang memiliki permukaan tidak rata serta menjaga kestabilan badan robot saat berjalan. Robot hexapod dipilih karena memiliki tingkat kestabilan yang baik saat berjalan. Robot hexapod berhasil diuji dalam enam kondisi bidang berbeda dan sepenuhnya mampu menjaga kestabilan di setiap pengujian seperti ketika berdiri diam di permukaan yang bergerak, berjalan di permukaan miring, pemukaan rumput maupun berpasir dengan dengan persen kesalahan kurang dari 10

The role of interstitial binding in radiation induced segregation in W-Re alloys

Due to their high strength and advantageous high-temperature properties, tungsten-based alloys are being considered as plasma-facing candidate materials in fusion devices. Under neutron irradiation, rhenium, which is produced by nuclear transmutation, has been found to precipitate in elongated precipitates forming thermodynamic intermetallic phases at concentrations well below the solubility limit. Recent measurements have shown that Re precipitation can lead to substantial hardening, which may have a detrimental effect on the fracture toughness of W alloys. This puzzle of sub-solubility precipitation points to the role played by irradiation induced defects, specifically mixed solute-W interstitials. Here, using first-principles calculations based on density functional theory, we study the energetics of mixed interstitial defects in W-Re, W-V, and W-Ti alloys, as well as the heat of mixing for each substitutional solute. We find that mixed interstitials in all systems are strongly attracted to each other with binding energies of -2.4 to -3.2 eV and form interstitial pairs that are aligned along parallel first-neighbor strings. Low barriers for defect translation and rotation enable defect agglomeration and alignment even at moderate temperatures. We propose that these elongated agglomerates of mixed-interstitials may act as precursors for the formation of needle-shaped intermetallic precipitates. This interstitial-based mechanism is not limited to radiation induced segregation and precipitation in W-Re alloys but is also applicable to other body-centered cubic alloys.Comment: 8 pages, 7 figure

K+^+ production in proton-nucleus reactions and the role of momentum-dependent potentials

The production of $K^+$ mesons in proton-nucleus collisions from 1.0 to 2.5 GeV is analyzed with respect to one-step nucleon-nucleon $(NN\to N Y K^+$) and two-step $\Delta$-nucleon $(\Delta N \to K^+ Y N$) or pion-nucleon $(\pi N \to K^+ Y$) production channels on the basis of a coupled-channel transport approach (CBUU) including the kaon final state interactions. The influence of momentum-dependent potentials for the nucleon, hyperon and kaon in the final state are studied as well as the importance of $K^+$ elastic rescattering in the target nucleus. The transport calculations are compared to the experimental $K^+$ spectra taken at LBL Berkeley, SATURNE, CELSIUS, GSI and COSY-J\"ulich. It is found that the momentum-dependent baryon potentials effect the excitation function of the $K^+$ cross section; at low bombarding energies of $\sim$ 1.0 GeV the attractive baryon potentials in the final state lead to a relative enhancement of the kaon yield whereas the net repulsive potential at bombarding energies $\sim$ 2 GeV causes a decrease of the $K^+$ cross section. Furthermore it is pointed out, that especially the $K^+$ spectra at low momenta (or kinetic energy $T_K$) allow to determine the in-medium $K^+$ potential almost model independently due to a relative shift of the $K^+$ spectra in kinetic energy that arises from the acceleration of the kaons when propagating out of the nuclear medium to free space, i.e. converting potential energy to kinetic energy of the free kaon.Comment: 11 pages, LaTeX, including 10 postscript figures, submitted to Eur. Phys. J.

Computation of laminar viscous-inviscid interactions in high-speed internal flows

A review is given of computations for a series of nominally 2-D laminar viscous-inviscid interactions. Comparisons were made with detailed experimental shock tunnel results. The shock wave boundary layer interactions considered were induced by a compression ramp in one case and by an externally generated incident shock in the second case. In general, good agreement was reached between the grid refined calculations and experiment for the incipient and small separation conditions. For the highly separated flow, 3-D calculations which included the finite span effects of the experiment were required in order to obtain agreement with the data

Cavitation damage in liquid metals technical progress report no. 467-3, 1 apr. - 31 may 1965

Cavitation damage resistance of refractory alloys in high temperature liquid sodiu

Cavitation damage in liquid metals technical progress report, 1 jan. - 31 mar. 1965

Temperature effect on rate of cavitation damage of 316 stainless steel in pure liquid sodium at temperatures up to 1500 deg