A Note on the Inverse Connected p-Median Problem on Block Graphs

Recently, the inverse connected p-median problem on block graphs G(V,E,w) under various cost functions, say rectilinear norm, Chebyshev norm, and bottleneck Hamming distance. Their contributions include finding a necessary and sufficient condition for the connected p-median problem on block graphs, developing algorithms and showing that these problems can be solved in O(n log n) time, where n is the number of vertices in the underlying block graph. Using similar technique, we show that some results are incorrect by a counter-example. Then we redefine some notations, reprove Theorem 1 and redescribe Theorem 2, Theorem 3 and Theorem 4.

Fundamental and Technical Challenges for a Compatible Design Scheme of Oxyfuel Combustion Technology

Oxyfuel combustion with carbon capture and sequestration （CCS） is a carbon-reduction technology for use in large-scale coal-fired power plants. Significant progress has been achieved in the research and development of this technology during its scaling up from 0.4 MWth to 3 MWth and 35 aWth by the combined efforts of universities and industries in China. A prefeasibility study on a 200 MWe large-scale demonstration has progressed well, and is ready for implementation. The overall research development and demonstration （RD＆D） roadmap for oxyfuel combustion in China has become a critical component of the global RD＆D roadmap for oxyfuel combustion. An air combustion/oxyfuel combustion compatible design philosophy was developed during the RD＆D process. In this paper, we briefly address fundamental research and technology innovation efforts regarding several technical challenges, including combustion stability, heat transfer, system operation, mineral impurities, and corrosion. To further reduce the cost of carbon capture, in addition to the large-scale deployment of oxyfuel technology, increasing interest is anticipated in the novel and next- generation oxyfuel combustion technologies that are briefly introduced here, including a new oxygen-production concept and flameless oxyfuel combustion.

Effect of different organic compounds on the preparation of CaO-based CO_(2) sorbents derived from wet mixing combustion synthesis

CaO based sorbents have great potential for commercial use to capture CO_(2) of power plants.In the demand of producing sorbents with better cyclic performance,CaO-based sorbents derived from different kinds of calcium precursors,containing calcium carbonate(CC-CaO),calcium gluconate monohydrate(CG-CaO),calcium citrate(CCi-CaO)and calcium acetate monohydrate(CA-CaO),were tested cyclically and compared using simultaneous thermal analyzer(STA).And further study was conducted on the sorbents modified with citric acid monohydrate and 50%gluconic acid solution by wet mixing combustion synthesis.The modified sorbents showed better performance and higher pore parameters as well as porous microstructure with more organic acid added.After 20 cycles of carbonation and calcination,the C2CCi8(CaO:citric acid=2:8 by mass ratio)and C2G8(CaO:gluconic acid=2:8 by mass ratio)sorbent possess CO_(2) capture capacity of 0.45g·g^(-1)(g CO_(2) per g sorbents)and 0.52 g·g^(-1) respectively.The citric acid was more effective for modification than gluconic acid for extended 50 cycles.Furthermore,good linear relationship between CaO conversion and specific surface area as well as pore volume were determined,of which the specific surface area showed closer correlation with CaO conversion。

Magma Generation of Magnetite-Rich Intermediate-Mafic Rocks and Its Mantle Processes in the Southwestern Alxa Block,NW China

Many studies focus on mineralization of huge magnetite ore deposits and petrogenesis of their large-volume host rocks.However,magma generation of those small-scale intrusions with enrichment of magnetite is poorly reported and paid attention to.We here carry out an integrated study of magnetite chemistry,U-Pb zircon dating,geochemistry,and Sr-Nd-Hf isotopes for the magnetite-rich intermediate-mafic rocks from the Helishan pluton in the southwestern Alxa Block,Northwest China.This,together with several previously reported magnetite/iron-rich intrusions nearby,is capable of providing some constraints on magma generation of magnetite/iron-rich intrusive rocks.The Helishan pluton,dated at ca.290 Ma,consists of hornblende gabbro,diorite,and quartz monzodiorite with~3%-5%magnetite in all the lithologies.Study on magnetite chemistry manifests a magmatic origin for them.All the lithologies display high TFeO/MgO ratio (1.71-1.89),weakly fractionated REE patterns((La/Yb)_(N)=1.82-10.17),enrichment of Rb,Sr,and Pb,and depletion of high field strength elements.They have (^(87)Sr/^(86)Sr)_(i) values of 0.705 2 to 0.705 8,ε_(Nd)(t) values of+0.03 to+0.64,and zircon ε_(Hf)(t) values of +6.5 to+12.0.We propose that they were derived from partial melting of iron-rich metasomatized lithospheric mantle.The systematic variations of Sr/Y ratios and Nd-Hf isotopic compositions with time for the Paleozoic igneous rocks at the southwestern Alxa Block indicate ever existence of thinning and rebirth of lithospheric mantle.This geodynamic process could be the potential mechanism to give rise to the iron-rich signature of the reborn mantle sources of the Helishan pluton.For intermediatemafic intrusions at subduction zones,they are unlikely to form considerable magnetite ore deposits since their modest magmatic flux and early fractional crystallization of magnetite at a high oxygen fugacity and H_(2)O condition.

Photonics-enabled distributed MIMO radar for high-resolution 3D imaging

Three-dimensional(3D)imaging radar is an advanced sensor applied in space surveillance and target recognition for supplying 3D geometric features and supporting visualization.However,high 3D resolution requires both broadband operation and a large 2D aperture,which are difficult and complex for conventional radars.This paper presents a photonics-enabled distributed multiple-input and multiple-output(MIMO)radar with a centralized architecture.By use of photonic multi-dimensional multiplexing,multi-channel signal generation and reception are implemented on a shared reference signal in a central office,enabling a highly coherent network with a simple structure.Additionally,a sparse array and a synthetic aperture are combined to efficiently reduce the required transceivers,further weakening the dilemma between system complexity and angular resolution.A 4×4 MIMO radar is established and evaluated in field tests.A high-resolution 3D image of a non-cooperative aircraft is obtained,in which rich details are displayed.From a comparison with electronics-based radar,significant resolution improvement is observed.The results verify the superior imaging capability and practicability of the proposed radar and its great potential to outperform conventional technologies in target classification and recognition applications.