Variable quiescent state for the neutron-star X-ray transient SAX J1750.8-2900: not such a hot neutron star after all?

We monitored the neutron star low-mass X-ray binary SAX J1750.8-2900 after the end of its 2015/2016 outburst using the X-ray Telescope (XRT) aboard Swift to detect possible post-outburst 'rebrightenings', similar to those seen after its 2008 outburst. We did not detect any rebrightening behaviour, suggesting that the physical mechanism behind the rebrightening events is not always active after each outburst of the source. Any model attempting to explain these rebrightenings should thus be able to reproduce the different outburst profiles of the source at different times. Surprisingly, our Swift/XRT observations were unable to detect the source, contrary to previous Swift/XRT observations in quiescence. We determined a temperature upper limit of $\leq$ 106 eV, much colder than the post 2008 outburst value of $\sim$ 145 eV. We also report on an archival Chandra observation of the source after its 2011 outburst and found a temperature of $\sim$ 126 eV. These different temperatures, including the non-detection very close after the end of the 2015/2016 outburst, are difficult to explain in any model assuming we observe the cooling emission from a neutron star core or an accretion-heated crust. We discuss our observations in the context of a change in envelope (the outer $\sim$ 100 m of the crust) composition and (possibly in combination with) a cooling crust. Both hypotheses cannot explain our results unless potentially unrealistic assumptions are made. Irrespective of what causes the temperature variability, it is clear that the neutron star in SAX J1750.8-2900 may not be as hot as previously assumed.Comment: Accepted for publication in MNRA

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

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

Experimental and analytical investigations on multiple liquid impact erosion

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

Comments on the role of diagonal dominance in implicit difference methods

Numerical tests were made for a model of the Navier-Stokes equations using a second-order accurate implicit scheme which guarantees diagonal dominance. The results suggest that the failure of implicit methods using large marching steps may not always be attributed to the lack of diagonal dominance in the coefficient matrix. In some cases the failure may be caused by a nonlinear instability associated with the solution method

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

PENGARUH MOTIVASI FINANSIAL, FAKTOR PSIKOLOGI DAN SUPERVISI TERHADAP KEPUASAN KERJA KARYAWAN PADA PT HAMUDA PRIMA SUKOHARJO

Setiap perusahaan selalu mengharapkan agar karyawan mampu bekerja dengan penuh semangat dan mencapai tingkat produktivitas yang tinggi. Hal tersebut dapat dicapai apabila perusahaan dengan karyawan saling menunjukkan hubungan kerja sama yang baik. Adapun tujuan dari penelitian ini adalah untuk mengetahui pengaruh motivasi finansial, faktor psikologi dan supervisi terhadap kepuasan kerja karyawan pada PT Hamuda Prima Media Sukoharjo. Sehingga berdasarkah hasil penelitian diharapkan menjadi pertimbangan bagi pimpinan khususnya PT Hamuda Prima Media Sukoharjo dalam upaya meningkatkan kepuasan kerja karyawan. Penelitian ini menggunakan penelitian survei dengan mengambil karyawan PT. Hamuda Prima Media Sukoharjo yang berjumlah 164 orang sebagai populasi penelitian. Sedangkan sampel penelitian diperoleh berdasarkan rumus Slovin sebesar 62 orang. Berdasarkan hasil penelitian diperoleh hasil bahwa perhitungan uji t untuk variabel motivasi finansial diperoleh thitung 2,104 > 2,002, artinya bahwa variabel motivasi finansial berpengaruh terhadap kepuasan kerja karyawan PT. Hamuda Prima Media Sukoharjo, untuk variabel faktor psikologi diperoleh thitung 2,538 > 2,002, artinya bahwa variabel faktor psikologi berpengaruh terhadap kepuasan kerja karyawan PT. Hamuda Prima Media Sukoharjo dan untuk variabel supervisi diperoleh thitung 2,084 > 2,002, artinya bahwa variabel supervisi berpengaruh terhadap kepuasan kerja karyawan PT. Hamuda Prima Media Sukoharjo. Adapun Nilai koefisien regresi tertinggi pada variabel motivasi finansial sebesar 0,296 berarti bahwa faktor yang paling dominan berpengaruh terhadap kepuasan kerja karyawan PT Hamuda Prima Media Sukoharjo adalah motivasi finansial. Hasil perhitungan uji F diperoleh Fhitung 37,497 > 2,76, artinya bahwa variabel motivasi finansial, faktor psikologi dan supervisi bersama-sama berpengaruh terhadap kepuasan kerja karyawan PT. Hamuda Prima Media Sukoharjo dan nilai koefisien determinasi (R2) adalah 0,660 berarti bahwa tingkat motivasi finansial, faktor psikologi dan supervisi dapat menjelaskan kepuasan kerja karyawan sebesar 66,0%, sedangkan sisanya sebesar 34,0% dapat dijelaskan oleh variabel lain diluar model

Extragalactic Background Light and Gamma-Ray Attenuation

Data from (non-) attenuation of gamma rays from active galactic nuclei (AGN) and gamma ray bursts (GRBs) give upper limits on the extragalactic background light (EBL) from the UV to the mid-IR that are only a little above the lower limits from observed galaxies. These upper limits now rule out some EBL models and purported observations, with improved data likely to provide even stronger constraints. We present EBL calculations both based on multiwavelength observations of thousands of galaxies and also based on semi-analytic models, and show that they are consistent with these lower limits from observed galaxies and with the gamma-ray upper limit constraints. Such comparisons "close the loop" on cosmological galaxy formation models, since they account for all the light, including that from galaxies too faint to see. We compare our results with those of other recent works, and discuss the implications of these new EBL calculations for gamma ray attenuation. Catching a few GRBs with groundbased atmospheric Cherenkov Telescope (ACT) arrays or water Cherenkov detectors could provide important new constraints on the high-redshift star formation history of the universe.Comment: 12 pages, 8 multi-panel figures, Invited talk at the 25th Texas Symposium on Relativistic Astrophysics, Heidelberg December 6-10, 201

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