Multi-Fidelity Gaussian Process Emulation And Its Application In The Study Of Tsunami Risk Modelling

Investigating uncertainties in computer simulations can be prohibitive in terms of computational costs, since the simulator needs to be run over a large number of input values. Building a statistical surrogate model of the simulator, using a small design of experiments, greatly alleviates the computational burden to carry out such investigations. Nevertheless, this can still be above the computational budget for many studies. We present a novel method that combines both approaches, the multilevel adaptive sequential design of computer experiments (MLASCE) in the framework of Gaussian process (GP) emulators. MLASCE is based on the two major approaches: efficient design of experiments, such as sequential designs, and combining training data of different degrees of sophistication in a so-called multi-fidelity method, or multilevel in case these fidelities are ordered typically for increasing resolutions. This dual strategy allows us to allocate efficiently limited computational resources over simulations of different levels of fidelity and build the GP emulator. The allocation of computational resources is shown to be the solution of a simple optimization problem in a special case where we theoretically prove the validity of our approach. MLASCE is compared with other existing models of multi-fidelity Gaussian process emulation. Gains of orders of magnitudes in accuracy for medium-size computing budgets are demonstrated in numerical examples. MLASCE should be useful in a computer experiment of a natural disaster risk and more than a mere tool for calculating the scale of natural disasters. To show MLASCE meets this expectation, we propose the first end-to-end example of a risk model for household asset loss due to a possible future tsunami. As a follow-up to this proposed framework, MLASCE provides a reliable statistical surrogate to a realistic tsunami risk assessment under a restricted computational resource and provides accurate and instant predictions of future tsunami risks

Potency of Sago Palm as Carbohydrate Resource for Strengthening Food Security Program

A new competition between biofuel production and food production has occurred in recent years, therefore the development of some new plant resources and their utilization are needed.  Sago palm and related species that can store a large amount of starch in the trunk and can grow under severe environmental conditions are considered to be potential starch resources for not only food production but also ethanol production.  However, even sago palm, an elite species among the starch producing palms, grows under semi-domesicated or natural condition and there are many problems to utilize it.  Thus, the systematic, ecological, physiological, agronomic and economic studies should be carried out for improvement of these species.  Here, the recent research progress is reviewed.  Large variation in morphological characteristics and palm size existed among the folk varieties of sago palm, and the difference in pith dry-matter yield was mainly attributable to trunk diameter and dry-matter content of the pith.  The two key parameters were closely related with soil profile indicating natural fertility.  On the other hand, the genetic distance of sago palm individuals grown in the Malay Archipelago was considered to be related to geographical distribution.  The genetic variation was small in the western area and large in the eastern area.  Sago palm tolerated up to 171mM (1.0%) NaCl concentration in the growth media for comparatively long period.  The salt resistance of sago palm might be due to salt avoidance to mechanically restrict an excess of Na distribution from the roots to leaflets.  The Na influx might be disturbed by the endodermal cells of roots even under 342mM (2.0%) NaCl condition.  Sago palm tolerated severe low pH condition such at pH 3.6 in the growth media for 5 months at least and maintained a low Al3+ concentration in the plant tissues.  Sago palm was considered to have a high tolerance to Al with the Al exclusion ability.  Moreover, the growth of sago palm was stimulated when AlCl3 was added into the growth media with 10ppm Al.  These physiological information on the growth response of sago palm to environmental stresses will be valuable for investigating concrete strategies to introduce new plant resources to barren lands with sterile soil and produce economic plants from poor productivity lands.   Key words:  acid soil, biofuel, genetic variation, Metroxylon, salt stress, starch

A mixed 0-1 programing approach to topology-finding of tensegrity structures

p. 569-576In this paper we propose an optimization-based approach to finding a tensegrity structure based on the ground structure method. We first solve a problem which maximizes the number of struts over the self-equilibrium condition and the discontinuity condition of struts. Subsequently we solve the minimization problem of the number of cables in order to remove redundant self-equilibrium modes. The optimization problem at each step can be formulated as a mixed integer programming (MIP) problem. The method does not require any connectivity information of cables and struts to be known in advance, while the obtained tensegrity structure is guaranteed to satisfy the discontinuity condition of struts rigorously.Ehara, S.; Kanno, Y. (2009). A mixed 0-1 programing approach to topology-finding of tensegrity structures. Editorial Universitat Politècnica de València. http://hdl.handle.net/10251/654

Expression of Ribonuclease Gene in Mechanically Injured or Virus-Inoculated Nicotiana tabacum Leaves

We characterized cDNAs encoding putative S-like RNases, RNase Nk1, Nk2 and Nk3, in Nicotiana tabacum L. cv. ky 57 leaf and examined the relation between these genes and Cucumber mosaic virus (CMV) infection. Of these genes, only RNase Nk1 was induced by wounding or CMV inoculation. The deduced amino acid sequence of RNase Nk1 is 97% identical to the N. alata RNase NE that is induced in roots in response to phosphate limitation. RNase Nk1 mRNA was highly induced in CMV-inoculated leaves within 3-6 hr after inoculation whereas a smaller increase was observed in mock- or CMV RNA-inoculated leaves. RNase Nk1 mRNA was also highly induced in leaves inoculated with CMV coat protein (CP) or BSA, suggesting that not only a mechanical damage but CP of CMV is the causal agent in the higher induction of RNase Nk1 gene immediately after virus infection in host plant cells