The Existence of Exponential Attractor for Discrete Ginzburg-Landau Equation

This paper studies the following discrete systems of the complex Ginzburg-Landau equation: iu˙m-(α-iε)(2um-um+1-um-1)+iκum+βum2σum=gm,  m∈Z. Under some conditions on the parameters α, ε, κ, β, and σ, we prove the existence of exponential attractor for the semigroup associated with these discrete systems

Effectiveness of Dynamic Compaction on Liquefied Foundation in Highway Practice

In this paper, the in-situ dynamic compaction tests with different values of single-drop-compaction energy are performed on a liquefiable ground encountered in highway engineering practice. Excess pore pressure, total surface settlement and lateral deformation under dynamic compaction impact are measured and analyzed at different conditions, such as single drop-compaction-energy, drop numbers, depth of soil layer etc. The standard penetration test (SPT) is used for investigating the compaction effectiveness. The investigation results indicate dynamic compaction technique is an effective way for improving liquefiable ground in highway engineering practice. Relatively small single-drop-compaction energy and relatively more drop numbers should be adopted for improving natural sedimentary liquefiable ground with dynamic compaction. The in-situ dynamic compaction tests show that the effective effect range by dynamic compaction impact depends on the single-drop-compaction energy. It is also found that the measured maximum lateral deformation has a good linear relationship with the total vertical surface settlement

Efficient and tunable liquid crystal random laser based on plasmonic-enhanced FRET

Random lasers (RLs), which possess peculiar advantages (e.g., emission and coherence tunable) over traditional lasers with optical resonators, have witnessed rapid development in the past decades. However, it is still a challenge to tune the lasing peak of an RL over a wide range. Here, a temperature-dependent Förster resonance energy transfer (FRET) RL is demonstrated in pyrromethene 597 (PM597, “donor”) and Nile blue (NB, “acceptor”) doped chiral liquid crystals. By changing the temperature that drives the liquid crystal bandgap shift, our RL device exhibits a lasing output change from 560 nm (yellow) to 700 nm (red). While the intrinsic FRET efficiency between PM597 and NB is relatively low, the red lasing is weak. By introducing gold nanorods (GNRs) into these RL devices and utilizing GNRs’ localized surface plasmon resonance (LSPR) effect, the efficiency of FRET transfer is increased by 68.9%, thereby reducing the threshold of the RL devices. By tuning the longitudinal LSPR to match the emission wavelength of NB, the best 200-fold lasing intensity enhancement is recorded. Our findings open a pathway toward realizing LSPR-enhanced FRET tunable RLs and broaden the range of their possible exploration in photonics research and technologies

Model tests on pervious concrete pile and impervious concrete pile composite foundation

Taking the advantages of high permeability and high strength, pervious concrete piles is suitable for improving ground bearing capacity and reduce the post-construction settlement, so pervious concrete pile composite foundation is a new foundation treatment. As pervious concrete piles were designed to accelerate soil consolidation and improve the ground bearing capacity, so model test of pervious concrete piles were conducted to evaluate the consolidation effect. Pervious concrete with porosity 20%, 25%, 30% and 35% was designed to compare the strength and permeability, and the porosity of 30% was selected, so the pile was made for the model test. Compared with impervious concrete pile composite foundation, as the pervious pile shortens the drainage path, pervious concrete pile composite foundation can shorten the consolidation time by about 30.3% and significantly reduce the peak value of excess pore pressure. With the increase of load and consolidation rate of soil around the pile, the stress ratio of pervious concrete pile increase first, then decrease and tend to be flat

Quality Assessment of Dry Soil Mixing Columns in Soft Soil Areas of Eastern China

To investigate the quality of dry soil mixing (DSM) columns in different soft soil areas of east China, a large number of laboratory test results and field test results of DSM columns were collected and analyzed statistically. Furthermore, a quality assessment method for DSM columns is proposed in this paper. The hardness description (HD), standard penetration test (SPT), unconfined compressive strength (UCS), and soil-cement column quality designation (SCQD) are used as assessment indexes. The statistical analysis showed that the test results of SPT, UCS, and SCQD were scattered, particularly in shallow ground. The mean values of the SPT blow count, UCS, and SCQD of the DSM columns decreased with depth: the greater the depth, the worse the quality of DSM columns. The quality assessment results showed that the proportion of the great quality columns was 64.84%, and the proportion of the unqualified columns was 1.4%. The proportion of DSM columns with great quality in the lagoon soft soil area was greater than in other areas. The proportion of unqualified columns in the lacustrine soft soil area was the largest. For all soft soil areas, the proportions of great quality, good quality, general quality, and unqualified soil decreased in that order. The quality assessment of 8627 DSM columns showed the proportions of great quality and unqualified were 64.84% and 1.4%, respectively. It was found that the greater the depth of the DSM column, the more unqualified DSM columns, and the more difficult it was to control the quality of DSM columns

Evaluation Method for the Liquefaction Potential Using the Standard Penetration Test Value Based on the CPTU Soil Behavior Type Index

Taking the project of the Su-xin highway treated by using the resonant compaction method as the reference, a new method for the evaluation of liquefaction potential is proposed based on the piezocone penetration test (CPTU) and the standard penetration test (SPT). The soil behavior type index (Ic) obtained from CPTUs and the standard penetration test index (N63.5), obtained from SPTs, are analyzed for saturated silty sand and silt. The analysis result reveals a linear relationship between N63.5 and Ic, given by N63.5=−18.8Ic+52.0. The larger the value of Ic is, the greater the viscosity of soil is, and the smaller the value of N63.5 is. According to the method, liquefaction assessment of saturated silty sand and silt foundation can be conducted by using N63.5 based on the Code of Seismic Design of Building. N63.5 is expressed by a single Ic, which is calculated from the CPTU data. Compared with existing evaluation methods, this method can provide continuous standard penetration test values, moreover, this method involves a simple calculation, and the results obtained using the method are reliable

Liquefiable Ground Treatment Using Cruciform Section Probe Resonant Compaction Method: A Case Study in the Xitong Expressway, Eastern China

The foundation treatment of liquefiable soil has always been an important part of construction. Sand liquefaction decreases the foundation capacity and can cause severe building, highway, or bridge engineering accidents. This study used self-developed cruciform section probe resonant compaction equipment (CSPRCE) to evaluate the applicability and reinforcement effect of the Xitong Expressway foundation. The cone penetration test (CPT) results showed that this soil was liquefiable ground requiring treatment before construction. Laboratory tests illustrated that the clay particle content was nearly 10% in the surface layer, indicating that the traditional resonant compaction probe (RCP) would not provide effective reinforcement; therefore, we adopted the new resonant compaction method (RCM) for the reinforcement process. The CPT and standard penetration test (SPT) results after foundation reinforcement indicated that the cruciform section probe resonant compaction method (CSPRCM) is suitable for treating the Xitong Expressway liquefiable foundation. Before reinforcement, 7-8 liquefiable soil layers were observed, whereas after reinforcement, no foundation testing points were liquefiable. Cone resistance and unit sleeve friction resistance were both improved by a factor of nearly 3 after the CSPRCM reinforcement. The CSPRCM has wider applicability than traditional vibrating compaction methods, especially for sites with a high content of silt and clay particles. The strengthening mechanism of the CSPRCM is a vibration hammer that generates vibrational energy to obliterate the original soil structure and render the sand completely liquefied; the soil particles then rearrange to form a new structure

Land wealth generation and distribution in the process of land expropriation and development in Beijing, China

<p>Based on transaction data at the parcel level in Beijing, this paper itemizes the costs incurred in the process of transferring rural land to urban development, quantifies the exact magnitude of land appreciation generated in this process and examines how the land wealth is distributed among involved parties. The main findings include the following: first, the land appreciation and the costs incurred in the process of land expropriation and primary development both differ from case to case; second, conventional comparison of the compensation for expropriated land with land granting price substantially overestimates the magnitude of land appreciation; the average and the median land appreciations account for 44.8% and 44.0% of the mean and median prices of granted serviced land, respectively; last, the compensation paid to affected farmers has improved in absolute terms during our study period from 2003 to 2014; however, because the land granting price has been escalating at a faster pace, the land wealth received by local governments has trended up.</p