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Impact of longer and heavier vehicles on the performance of asphalt pavements: A laboratory study
Published in Andreas Loizos, Imad L. Al-Qadi, A. (Tom) Scarpas, Bearing Capacity of Roads, Railways and Airfields, 2017
A.W. Ahmed, M.S. Rahman, S. Erlingsson
Akerman & Jonsson (2007), Aurell & Wadman (2007) and Leduc (2009) employed similar procedures based on the fourth power law to compare LHVs scenarios for current and prospective modular vehicle combinations with a total length greater than 25.25 m. Their studies concluded that the road wear from LHVs was typically less than from vehicle combinations permitted under EU regulations. It should be noted that the studies based on the fourth power law assumed that the LHVs scenarios do not necessarily result in higher axle loads. Also, the ESALs per ton are normalized with the GVW, and thus the results may vary if the LHVs are not fully loaded. Furthermore, several studies have questioned the validity of the fourth power law for conditions different from the AASHTO test roads used to empirically derive the fourth power law (Cebon, 1999).
DSP-Based Coherent Optical Transmission Systems
Published in Le Nguyen Binh, Digital Processing, 2017
Nyquist pulse shaping is one of the efficient methods to pack adjacent subchannels into a superchannel. The timing recovery of such Nyquist subchannels is critical for sampling the data received and improving the transmission performance. Timing recovery can be done either before or after the PMD compensator. The phase detector scheme is shown in Figure 7.28, a Godard type [12], which is a first-order linear scheme. After CD compensation (CD−1 blocks), the signal is sent to a state-of-polarization (SOP) modifier to improve the clock extraction. The clock performance of an NRZ QPSK signal in the presence of a first-order PMD characterized by a differential group delay (DGD) and azimuth is presented in Figure 7.3. The azimuth of 45° and DGD of a half symbol/unit interval (UI) completely destroys the clock tone. Therefore, the SOP modifier is required for enabling the clock extraction. In practical systems, a raised-cosine filter is used to generate Nyquist pulses. A filter pulse response is defined by two parameters, the ROF β and the symbol period Ts, and described by taking the inverse Fourier transform of Equation 7.4. The Godard phase detector cannot recover the carrier phase, even with small β; thus, the channel spectra is close to rectangular. A higher-order phase detector must be used to effectively recover the timing clock period as shown in Ref. [13]. A fourth-power law PD (4PPD) with prefiltering presented in Ref. [14] and as shown in β values. Figure 7.28b can deal with small β values.
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Published in Carl W. Hall, Laws and Models, 2018
Also represented by the square root of the Weber number (No. 1) the Reynolds number. Keywords: capillary jets, slosh, surface tension, viscous Sources: Bolz, R. E. and Tuve, G. L. 1970; Land, N. S. 1972; Parker, S. P. 1992; Potter, J. H. 1967. See also REYNOLDS; WEBER OHNO LAW (GENETICS) The x-inactivation mechanism has preserved the ancestral x-chromosomes almost intact during the evolution of mammals. The inactivation of one x-chromosome compensates for different dosages of x-linked alleles in males and females, ensuring genetic balance in both sexes. Keywords: alleles, chromosome, evolution, female, male, mammals Source: Morris, C. G. 1992. OKUN LAW (1968) Relates the loss in aggregate output that is statistically associated with a given short-run increase in the unemployment rate. The law states that the elasticity of the ratio of actual to potential real output with respect to a change in the employment rate is a constant, roughly equal to 3.0. Keywords: aggregate output, economics, elasticity, employment, output OKUN, Arthur M., 1928-1980, American economist Sources: Pearce, D. W. 1981; Who's Who in America. 1976. OLLIER LAW With two parallel bones that are joined at their extremities by ligaments, the arrest of growth in one of the bones involves the disturbance of growth in the other. Keywords: bones, growth, ligaments OLLIER, Leopold Louis Xavier Edouard, 1830-1900, French surgeon Sources: Friel, J. P. 1974; Landau, S. I. 1986. OLIGOMERIZATION, LAW OF (ECOLOGICAL); ALSO KNOWN AS LAW OF INTEGRATION An evolutionary trend manifesting a reduction in the number of segments of a body or structure. Keywords: evolutionary, reduction, segments Source: Lincoln, R. 1982. ONE-FOURTH POWER LAW--SEE ALLOMETRIC SCALING LAW ONE-SEVENTH POWER--SEE PRANDTL
Nondestructive testing algorithm of building concrete material defects based on machine learning
Published in Journal of Control and Decision, 2023
When the time t is greater than 0, X is zero, and the boundary is the radiation heating of the receiving sun. The radiation heating follows the fourth power law, and the ambient temperature is a constant Tw. The total solar heating output produced from either a surface is proportional to the average of its actual temperature, according to the fourth power law. Even blackbodies, hypothetical coverings that absorbed all incoming radiant heat, are subject to the law. The mathematical expression is as follows: where TS represents the temperature of the heating surface in the defect-free area. The proposed concrete material is the ideal material:
Traffic channelisation and pavement deterioration: an investigation of the role of lateral wander on asphalt pavement rutting
Published in International Journal of Pavement Engineering, 2022
A large body of literature has found many factors that influence pavement deterioration, and hence lifespan. The critical determinant is the amount and type of traffic exerting a load on the pavement surface (Atkinson et al., 2006, Blab and Litzka, 1995, Buiter et al., 1989). The traffic load is distributed to the pavement through the axles, wheels and then the tyres of the vehicles (Pais et al., 2013). Hence, various design standards and guides convert different vehicle types into standard axle loads and wear factors (Highways Agency, 2006a). In the UK, the wear factors specified in the design standard (Highways Agency, 2006b) are derived from the fourth power law, where the damaging effect is proportional to the fourth power of the load exerted by a vehicle’s wheel onto the surface. Studies and design codes around the world highlight that load repetitions by heavy vehicles in particular results in considerable deterioration, which could be up to a power of 7 of the traffic load for chip sealed pavements (Collop, 2002, Erlingsson et al., 2012, Blab and Litzka, 1995, van der Walt et al., 2017a). While there is a large body of evidence as to the damaging effect of different vehicle types on the pavement; there is less evidence and guidance as to whether the distribution of traffic loads over the cross-section of the pavement influences this.
Assessment of the Maximum Temperature of Simplified High Heat Radioactive Glass in Interim Storage and Deep Geological Disposal
Published in Nuclear Technology, 2021
Overall, the room temperature air freely enters the bottom of the vault and is heated by the canisters. A linear increasing tendency of air temperature along the vertical axis and the existing air temperature to ~80°C reported in the spent nuclear fuel contained in a 4-m-height cylindrical cask.14,16,32 Hence, the air temperature gradient inside the vault was set to have linearity based on the geometric similarity. Yet the existing air temperature at the top of the vault can be varied depending on the different scenarios. Normally, the air inside the interim storage needs to circulate to avoid unwanted heat accumulation in the system. However, one possibility of further heated air at the top can occur for any reason, for example, failure of an appropriate ventilation system and blockage of an airway. Thus, modeling for further heated exiting air is considered to show the range of maximum temperature in interim storage. Based on the thermal stability estimation, the heated air temperature was 145°C and 150°C for 15.8 and 18.6 kW/m3, respectively. Radiative heat transfer between objects and structures is applied. Surface-to-surface radiative heat transfer is governed by the fourth power law [Eq. (9)]: