Scaled experimental study on excavation of lunar regolith with rakes/rippers and flat blade

As humanity\u27s activities expand to the Moon, Mars, and other extra-terrestrial bodies, it will be necessary to use local resources rather than bringing everything from the Earth. This concept is called In-Situ Resource Utilization (ISRU), which starts with excavation and earthmoving. The present study focuses on loosening and moving of the lunar regolith by a ripper (or rake) and a wide blade with consideration of gravel content. After characterizing the lunar regolith and two of its simulants (JSC-1A and FJS-1), the relationship between the excavation energy and different conditions, namely gravel content, relative density, and tine spacing on a rake, is investigated with scaled experiments. Geotechnical properties of JSC-1A were determined, in addition to the simulants\u27 stress-strain relationships over a wide range of relative density (13% to near 100%). Gravel content of the lunar regolith, often overlooked in previous studies, is estimated based on the data of 11 Apollo cores, which reveals the maximum local gravel content is about 30% by weight. Also the grain size distribution of the lunar regolith up to 1 m grains is created by combining the data from Apollo and Surveyor missions. In the experiments, gravel (2 mm - 10 mm) is added to JSC-1A. In addition, a math model of the ripping force is developed as a function of material density, which could be the basis of an instrumented-ripper technique for detailed mapping of construction. Prior ripping decreases total excavation energy by up to 20% if the relative density is ≥ 60% and the gravel content is ≤ 10%. The optimal tine spacing for JSC-1A at a penetration depth of 30 mm is 30 mm. Even a gravel content of 5% increases the reaction force on excavation tools, which underlines the necessity of consideration of gravel content for lunar excavation planning --Abstract, page iii

Recent Studies on Seismic Analysis and Design of Retaining Structures

The studies on seismic analysis and design of retaining walls in the recent years have revolved around the wall performance in the near-source zones. Major developments include: (1) the conventional limit equilibrium approach is extended based on the multiple failure plane concept; (2) a set of design charts for evaluating residual horizontal displacement of a gravity wall on yielding foundation are developed based on the parametric effective stress analysis; (3) applicability of the effective stress analysis on the retaining wall performance is confirmed by the case history during Hyogoken-Nambu, Kobe, earthquake; (4) major earthquake motion parameters that govern the wall displacement through soil-structure interaction analysis are spectral intensity (damping factor-20% and integration over 1.0 to 3.0 seconds) and/or frequency components lower than about 2Hz, which is lower than the fundamental natural frequency of the wall-soil system at small strain shaking. These developments in the seismic analysis of retaining walls lead us toward the performance-based design of retaining walls

Recent Earthquakes in Japan

The paper presents highlights of case histories during earthquakes in Japan in 2003. One is a river embankment of the Naruse river in Northern Miyagiken, in which the earthquake with Richter magnitude 6.2 caused failure. A particular interest in this case history is the timing of the earthquake and failure; the earthquake was coincided with the oncoming risk of flooding, with the river suffering a high water level due to continuous raining for three days before the earthquake. This warns us not to disregard the low probability event of combined risks that pose high consequence. The other case history is a gravity quay wall in Kushiro port, Hokkaido, in which the earthquake with Richter magnitude 8.0 caused minor damage. Of a particular interest in this case history is the performance of a quay wall with backfill treated with cement for solidification, which suffered settlements in the order of 0.5m. Other quay walls in the vicinity treated with densification and gravel drains suffered no damage. The investigation is under way with respect to the difference in the performance of these quay walls

Adjustment Method of the Hysteresis Damping for Multiple Shear Spring Model

In simulating the behavior of sandy soil under the cyclic loading condition using the multiple shear spring model, it is necessary to adjust the damping constant of the model. We describe a method for adjusting the constant in this paper. If you adopt the conventional Masing rule to decide the unloading curve of each spring, the entire damping constant of this model, which is superposition of those of all springs, would become larger than that measured in the laboratory for large strain level. Though the damping constant of each spring is controllable by amending the Masing rule, there is no obvious way to decide the constant of each spring. In order to reproduce the actual damping constant, we expressed the damping constant of each spring as a function of displacement at which unloading of the spring has started, and determined the coefficients of the expression from the actual damping constant. So we can amend the Masing rule for each spring so as to realize the damping constant for each spring. The method is adopted to the effective stress analysis program FLIP developed by the authors. In this paper we explain the method and show the results of the computer simulations by FLIP program

Gorensteinness in Rees algebras of powers of parameter ideals

This paper gives a necessary and sufficient condition for Gorensteinness in Rees algebras of the $d$-th power of parameter ideals in certain Noetherian local rings of dimension $d\ge 2$. The main result of this paper produces many Gorenstein Rees algebras over non-Cohen-Macaulay local rings. For example, the Rees algebra $\mathcal{R}(\mathfrak{q}^d)=\oplus_{i\ge 0}\mathfrak{q}^{di}$ is Gorenstein for every parameter ideal $\mathfrak{q}$ that is a reduction of the maximal ideal in a $d$-dimensional Buchsbaum local ring of depth 1 and multiplicity 2.Comment: 29 page

Pengaruh Periklanan Dan Ketidakpuasan Terhadap Keinginan Berpindah Merek Oleh Konsumen Laptop Di Kota Banda Aceh

Penelitian ini bertujuan untuk mengetahui seberapa besar pengaruh periklanan dan ketidakpuasan konsumen laptop di Kota Banda Aceh terhadap keinginan berpindah merek. Model analisis dalam penelitian ini adalah regresi linier berganda. Jumlah sampel yang digunakan dalam penelitian ini sebanyak 100 responden yang diambil dengan menggunakan metode purposive sampling. Hasil penelitian berdasarkan uji t diperoleh nilai thitung sebesar 1,383 untuk variabel periklanan dan 7,898 untuk variabel ketidakpuasan, sedangkan nilai ttabel sebesar 1,984. Berdasarkan hasil tersebut dapat dinyatakan bahwa secara parsial hanya variabel ketidakpuasan yang berpengaruh signifikan terhadap keinginan berpindah merek, sedangkan variabel periklanan tidak berpengaruh signifikan

Numerical Analysis of Trampoline Effect in Extreme Ground Motion

Very large vertical surface acceleration of nearly four times gravity was measured at a strong motion observation station in Iwate Prefecture during the 2008 Iwate-Miyagi Inland, Japan, earthquake (Mw 6.9). The station is located about 3 km southwest of the epicenter and equipped with three-component accelerometers, installed at both the free surface and the bottom of a 260-m borehole. The wave form of the vertical acceleration shows a clearly asymmetric form with large amplitude in the upward direction. Aoi et al. (2008) reported and qualitatively explained the mechanism of this phenomenon by the analogy of bouncing a piece of matter on a trampoline, and thus they called it the “trampoline effect.” To simulate this recently discovered nonlinear behavior of the surface ground motion, numerical analysis with a finite-element method has been employed with parameters derived from the borehole data at the station. The analysis successfully simulates the asymmetric vertical motion. Results indicate that the asymmetric motion may be characterized by the existence of a lower bound of negative acceleration, which in most cases corresponds to the acceleration of gravity, and high positive pulses caused by the compression stress of the disturbed surface ground material

Effective Stress Analysis for Evaluating the Effect of the Sand Compaction Pile Method During the 1995 Hyogoken-Nambu Earthquake

The effect of the sand compaction pile method as a countermeasure for liquefaction mainly consists of three factors: increase in the density, increase in the horizontal effective stress and stabilization of microstructure. Proper evaluation of the effect of improvement is important for estimating the seismic behavior of the ground improved by the sand compaction pile method. How to incorporate the effect and its factors into an analytical model was investigated by simulating the seismic behavior of the ground at two sites during the 1995 Hyogoken-Nambu earthquake with the effective stress analysis method “FLIP.” It was found that not only the increase in the density but also increase in the horizontal effective stress were important in explaining the effect of the sand compaction pile method. Moreover, a model taking account of both sand piles and the improved ground between them suggested a possibility of reproducing the behavior of improved ground under large ground motions more properly