In view of some shortcomings of traditional vertex 1-center (V1C), we introduce a vertex quickest 1-center (VQ1C) problem on a tree, which aims to find a vertex such that the maximum transmission ...time to transmit Formula omitted units data is minimum. We first characterize some intrinsic properties of VQ1C and design a binary search algorithm in Formula omitted time based on the relationship between V1C and VQ1C, where n is the number of vertices. Furthermore, we investigate the inverse VQ1C problem under weighted Formula omitted norm, in which we modify a given capacity vector in an optimal way such that a prespecified vertex becomes the vertex quickest 1-center. We introduce a concept of an effective modification and provide some optimality conditions for the problem. Then we propose an Formula omitted time algorithm. Finally, we show some numerical experiments to verify the efficiency of the algorithms.
The max+sum spanning tree (
MSST
) problem is to determine a spanning tree
T
whose combined weight
max
e
∈
T
w
(
e
)
+
∑
e
∈
T
c
(
e
)
is minimum for a given edge-weighted undirected network
G
(
V
,
...E
,
c
,
w
). This problem can be solved within
O
(
m
log
n
)
time, where
m
and
n
are the numbers of edges and nodes, respectively. An inverse
MSST
problem (
IMSST
) aims to determine a new weight vector
w
¯
so that a given
T
0
becomes an optimal
MSST
of the new network
G
(
V
,
E
,
c
,
w
¯
)
. The
IMSST
problem under weighted
l
∞
norm is to minimize the modification cost
max
e
∈
E
q
(
e
)
|
w
¯
(
e
)
-
w
(
e
)
|
, where
q
(
e
) is a cost modifying the weight
w
(
e
). We first provide some optimality conditions of the problem. Then we propose a strongly polynomial time algorithm in
O
(
m
2
log
n
)
time based on a binary search and a greedy method. There are
O
(
m
) iterations and we solve an
MSST
problem under a new weight in each iteration. Finally, we perform some numerical experiments to show the efficiency of the algorithm.
The max+sum spanning tree (MSST) problem is to determine a spanning tree T whose combined weight Formula omitted is minimum for a given edge-weighted undirected network G(V, E, c, w). This problem ...can be solved within Formula omitted time, where m and n are the numbers of edges and nodes, respectively. An inverse MSST problem (IMSST) aims to determine a new weight vector Formula omitted so that a given Formula omitted becomes an optimal MSST of the new network Formula omitted. The IMSST problem under weighted Formula omitted norm is to minimize the modification cost Formula omitted, where q(e) is a cost modifying the weight w(e). We first provide some optimality conditions of the problem. Then we propose a strongly polynomial time algorithm in Formula omitted time based on a binary search and a greedy method. There are O(m) iterations and we solve an MSST problem under a new weight in each iteration. Finally, we perform some numerical experiments to show the efficiency of the algorithm.
Based on the 2,2-dipicolylamine (DPA) receptor and naphthalimide fluorophore, three fluorescent probes, RDPA, MDPA and VDPA have been developed for the recognition of mercuric ions. Among them, VDPA, ...bearing a diglycol group in the imine chain, exhibits good water solubility, and high selectivity towards mercuric ions in PBS water solution. With DPA as the receptor, VDPA showed very high affinity and sensitivity towards Hg(2+), and the binding constant and detection limit were calculated to be 2.8 × 10(10) M(-1) and 5.49 nM, respectively. The MTT assay and living cell imaging experiments suggested that the probe VDPA has potential application for detecting Hg(2+) in living cells.
This paper establishes a bilevel planning model with one master and multiple slaves to solve traffic evacuation problems. The minimum evacuation network saturation and shortest evacuation time are ...used as the objective functions for the upper- and lower-level models, respectively. The optimizing conditions of this model are also analyzed. An improved particle swarm optimization (PSO) method is proposed by introducing an electromagnetism-like mechanism to solve the bilevel model and enhance its convergence efficiency. A case study is carried out using the Nanjing Olympic Sports Center. The results indicate that, for large-scale activities, the average evacuation time of the classic model is shorter but the road saturation distribution is more uneven. Thus, the overall evacuation efficiency of the network is not high. For induced emergencies, the evacuation time of the bilevel planning model is shortened. When the audience arrival rate is increased from 50% to 100%, the evacuation time is shortened from 22% to 35%, indicating that the optimization effect of the bilevel planning model is more effective compared to the classic model. Therefore, the model and algorithm presented in this paper can provide a theoretical basis for the traffic-induced evacuation decision making of large-scale activities.
The U.S-China trade relationship has undergone tremendous growth since 1979 when the United States and China establish their diplomatic relationship. The trade volumes have increased dramatically ...after China joined the World Trade Organization in 2001. Recently, the trade relationship between the two countries has experienced some setbacks?specially in terms of the huge U.S trade deficits with China, the currency manipulation by the Chinese government, and China’s failure in enforcing strict laws to protect intellectual property rights(IPR) of U.S companies. Effective solutions to address such trade frictions may involve consideration of trade policies, negotiation, and cooperation between the two countries. This article first provides an overview the current trade status and friction between U.S and China. Next, the possible root causes of such tensions are explored. Finally, possible solutions are presented to alleviate such tensions and to all both countries benefit from a mutually harmonious trade relationship
Reaction of 4,4′-bipyridine-N,N′-dioxide (L) with a variety of transition-metal salts in MeOH affords a range of coordination polymer products. For the complexes FeCl3(μ-L)∞, 1, and ...(Cu(L)2(OHMe)2(μ-L)·2PF6·n(solv))∞, 2, 1D chain structures are observed, whereas (Mn(μ-L)3·2ClO4)∞, 3, and (Cu(μ-L)3·2BF4)∞, 4, both show 2D sheet architectures incorporating an unusual 36-hxl topology. The more common 44-sql topology is observed in Cd(ONO2)2(μ-L)2∞, 5, (Cu(OHMe)2(μ-L)2·2ZrF5)∞, 6, (Cu(L)2(μ-L)2·2EF6)∞ (7 E = P; 8 E = Sb), and (Et4NCu(OHMe)0.5(μ-L)2(μ-FSiF4F)0.5·2SbF6·n(solv))∞, 9. In 6, the ZrF5− anion, formed in situ from ZrF62−, forms 1D anionic chains (ZrF5−)∞ of vertex-linked octahedra, and these chains thread through a pair of inclined polycatenated (Cu(OHMe)2(μ-L)22+)∞ 44-sql grids to give a rare example of a triply intertwined coordination polymer. 9 also shows a 3D matrix structure with 44-sql sheets of stoichiometry (Cu(L)22+)∞ coordinatively linked by bridging SiF62− anions to give a structure of 5-c 44.66-sqp topology. The mononuclear Cu(L)6·2BF4 (10) and Cd(L)6·2NO3 (11) and binuclear complexes (Cu(L)(OH2))2(μ-L)2)·2SiF6·n(solv), 12, are also reported. The majority of the coordination polymers are free of solvent and are nonporous. Thermal treatment of materials that do contain solvent results in structural disintegration of the complex structures giving no permanent porosity.
A robust 3-D porous structure of formula Ln2(PDC)3(DMF)2∞ has been constructed from lanthanide cations (Ln = Er3+ or Y3+) and the non-linear anionic bridging ligand, pyridine-3,5-dicarboxylate ...(PDC2-) in dimethylformamide (DMF). The solvated framework polymers {M2(PDC)3(DMF)2·n(solv)}∞ (M = Er, Y) undergo a solid-state, crystal-to-crystal reaction upon heating and are converted via loss of both sorbed and coordinated solvent and rearrangement of the framework core to give a desolvated and porous form with retention of structural integrity. This structural transfer is the first crystallographically characterized system with lanthanide metal ions. These porous products are shown to be effective absorbants for H2, N2, and benzene.
In the field of equipment maintenance support, information technology presents some characteristics. The first is integration of command information system function. The second is intelligent of ...support equipment and technical means. The third is integration of information technology of military and civilian. To promote the informatization construction of equipment maintenance support, we need to scientifically formulate the development plan for the application of information technology in the field of equipment maintenance support, strengthen the construction of the security capability of the equipment maintenance support information system, and strengthen the risk management of the supply chain of equipment and facilities in the field of equipment maintenance support.
The mechanism and intermediates in the UV-light-initiated ligand rearrangement of fac-Re(diimine)(CO)3Cl to form the mer isomer, when incorporated into a 3D metal–organic framework (MOF), have been ...investigated. The structure hosting the rhenium diimine complex is a 3D network with the formula {Mn(DMF)2LRe(CO)3Cl}∞ (ReMn; DMF = N,N-dimethylformamide), where the diimine ligand L, 2,2′-bipyridine-5,5′-dicarboxylate, acts as a strut of the MOF. The incorporation of ReMn into a KBr disk allows spatial distribution of the mer-isomer photoproduct in the disk to be mapped and spectroscopically characterized by both Fourier transform infrared and Raman microscopy. Photoisomerization has been monitored by IR spectroscopy and proceeds via dissociation of a CO to form more than one dicarbonyl intermediate. The dicarbonyl species are stable in the solid state at 200 K. The photodissociated CO ligand appears to be trapped within the crystal lattice and, upon warming above 200 K, readily recombines with the dicarbonyl intermediates to form both the fac-Re(diimine)(CO)3Cl starting material and the mer-Re(diimine)(CO)3Cl photoproduct. Experiments over a range of temperatures (265–285 K) allow estimates of the activation enthalpy of recombination for each process of ca. 16 (±6) kJ mol–1 (mer formation) and 23 (±4) kJ mol–1 (fac formation) within the MOF. We have compared the photochemistry of the ReMn MOF with a related alkane-soluble Re(dnb)(CO)3Cl complex (dnb = 4,4′-dinonyl-2,2′-bipyridine). Time-resolved IR measurements clearly show that, in an alkane solution, the photoinduced dicarbonyl species again recombines with CO to both re-form the fac-isomer starting material and form the mer-isomer photoproduct. Density functional theory calculations of the possible dicarbonyl species aids the assignment of the experimental data in that the ν(CO) IR bands of the CO loss intermediate are, as expected, shifted to lower energy when the metal is bound to DMF rather than to an alkane and both solution data and calculations suggest that the ν(CO) band positions in the photoproduced dicarbonyl intermediates of ReMn are consistent with DMF binding.
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