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991.
为探究我国出口集装箱班轮运价的周期性,提高对集装箱班轮运输行业周期性的认识,以中国出口集装箱运价指数(CCFI)作为我国出口集装箱班轮运价的测度指标,分析其周期性,发现1个循环周期大约4年,与世界经济周期有较大相关性,随贸易额的涨跌而变动,季节周期表现为夏秋高、冬春低的特点,运价从3—4月的最低点上升到9—10月的最高点,此后逐渐下降,每年1个周期。 相似文献
992.
This paper determined the existence of λ-fold pure Mendelsohn triple system of order υ satisfying λυ(υ-1)≡0 (mod 3) and υ≥4λ 5, or υ=2λ 2, and in the case of λ=4,5,6, which completely settled their existence. 相似文献
993.
Let ARDkCS(v) denote an almost resolvable directed k-cycle system of order v. It is clear that a necessary condition for the existence of an ARDkCS(v) is v=1(mod k). For k:3,4,5 and 6, the existence of an ARDkCS (v) had been completely solved. This paper shows that there exists an ARD7CS(v) if and only if v≡1 (rood 7) and v≥8. 相似文献
994.
通过对NaOH-H2O-C2H5OH-Na2SO4(NaCl)体系相平衡规律的研究,提出了循环利用阴离子交换树脂再生溶液的方法,该方法利用乙醇调整再生液体系的相平衡,分离出再生产物,实现再生液循环使用,防止了水体污染和资源浪费。 相似文献
995.
超循环理论是M·艾根等创建的一个较为完整的自组织理论,该理论运用反应循环、催化循环、催化超循环三个循环,系统诠释了生物进化无机物到生命细胞的形成过程。在系统分析思想的指导下,文中将超循环理论应用到交通影响分析阀值的研究中,提出了一种研究阀值的新方法——超循环理论法。该方法运用系统动力学及不动点理论建立模型,通过对模型的求解,确定最终阀值。该方法的运用,简化了阀值研究程序,节省了阀值分析时间,具有较强的操作性。 相似文献
996.
By using the soil static and dynamic universal triaxial and torsional shear apparatus, a series of combined cyclic shear tests are performed to simulate the rotation in the principal stress direction induced by ocean wave. The tests include the cyclic preloading tests and liquefaction tests in the second loading on saturated loose sand with a relative density of 30%. The all tests are consolidated under isotropic condition. The effect of the cyclic preloading on the resistance to liquefaction of saturated loose sands under the condition of continuous rotation in the principal stress direction is investigated. Experimental data indicate that the void ratio of saturated sands has a negligible reduction after cyclic preloading. With the increase of the intensity of cyclic preloading (in the amplitude and in the number of cycles), the resistance to liquefaction in the second loading is increased continuously under the condition that the liquefaction does not occur during the cyclic preloading. The reason is that the construction of more stable structure due to the uniformity of the void and the better interlocking of the particles when the cyclic preloading is applied to the saturated sand. 相似文献
997.
To implement the primary signal without interference in cognitive radio systems, cognitive radios can detect the presence
of the primary user in low SNR. Currently, energy detector is the most common way of spectrum sensing because of its low computational
complexity. However, performance of the method will be possibly degraded due to the uncertainty noise. This paper illustrates
the benefits of one-order and two-order cyclostationary properties of primary user’s signals in time domain. These feature
detection techniques in time domain possess the advantages of simple structure and low computational complexity comparing
with spectral feature detection methods. Furthermore, performance of the one-order and two-order feature detection is studied
and the analytical results are given. Our analysis and numerical results show that the sensing performance of the one-order
feature detection is improved significantly comparing with conventional energy detector since it is robust to noise. Meanwhile,
numerical results show that the two-order feature detection technique is better than the one-order feature detection. However,
this benefit comes at the cost of hardware burdens and power consumption due to the additional multiplying algorithm. 相似文献
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