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排序方式: 共有236条查询结果,搜索用时 31 毫秒
1.
The draft Long-Term 2 Enhanced Surface Water Treatment Rule (LT2ESWTR) contains Cryptosporidium log-inactivation CT tables (ozone-in-water concentration [residual], “C” times contact time, T). Depending on water temperature, Cryptosporidium CT values that are listed are 15 to 25 times greater than CT values for equivalent Giardia log-inactivation credit. The elevated operating dose required for Cryptosporidium log-inactivation credit has the potential to increase disinfection by-product (DBP) formation (e.g., bromate). Calculating CT value accurately will minimize ozone dose, which will decrease operating cost and lower DBP formation, and at the same time maintain disinfection protection through implementation of scientifically based safety factors. Various methods are available for calculating CT value. The method chosen depends largely on the available information concerning ozone residual characteristics and hydrodynamic features of the ozone contactor, plus local regulatory requirements. Four methods are discussed in this paper. Each method can be used to calculate Giardia, virus, and Cryptosporidium log-inactivation credit. 相似文献
2.
This paper evaluates the behavior and performance of laminated circular elastomeric bearings and compares them to those of square and rectangular bearings. The study included an experimental evaluation and a nationwide survey of state Department of Transportations on the use and performance of circular bearings and bearings in general in their states. The experimental investigation studied the bearings' behavior in compression, compression and rotation, and compression and shear. Results from this limited study showed that the three bearings have similar stress-strain behavior in compression and they are in agreement with the AASHTO LRFD guide stress–strain curves. In compression and rotation, the AASHTO LRFD substructure moments are slightly less than the measured values for circular bearings and rectangular bearings rotated about their strong axis for a compressive stress of 10.3?MPa (1.5?ksi) and slightly higher than those of rectangular bearings rotated about their weak axis. In compression and shear, the shear stiffness of circular and square bearings is in agreement with theoretical values within the range of design displacements. Results from the survey showed that many states are using circular bearings and more states would consider using them, however no maintenance or monitoring data were available on their short-term and long-term performance. 相似文献
3.
Qingbin Cui Mehmet Emre Bayraktar Makarand Hastak Issam Minkarah 《Canadian Metallurgical Quarterly》2004,20(3):118-125
Since the introduction of warranty provisions in federal highway jobs, more and more state departments of transportation (DOTs) have considered the use of such provisions to protect their initial investment. This paper describes the pros and cons of warranty contracting in highway construction based on a survey of warranty practices in the United States. In particular, the need for state DOTs to buy a warranty for a well-built project is questioned. As an alternative, this paper introduces the warranty option, which gives the DOT the right to buy a warranty only if it becomes necessary at the end of construction. This option is exercised if the performance on site warrants it. This paper describes the mechanics of the warranty option and its advantages over the conventional warranty. A bid evaluation model is also developed for the warranty option approach. 相似文献
4.
Issam El Gmati Pierre Francois Calmon Ali Boukabache Patrick Pons Hatem Boussetta Mouhamed Adel Kallala Kamel Besbes 《Microsystem Technologies》2014,20(6):1085-1091
In this work, RF MEMS continuous reversible variable inductor has been fabricated by using microelectronic technology and lamination process. We review, evaluate and compare this variable inductor with other work. The proposed inductor is a dual circular coil and has an inductance of few nH. The fundamental idea is to place a liquid droplet between the metal turns of a coil in order to modify the capacitive/resistive coupling between metal tracks and hence to change the stored magnetic energy. The SU-8 resin was used to realize the microfluidic channels and Au as metallic tracks. To prove the reversibility of the inductor, two cases were studied: filling and emptying of channels. The tuning range of the inductance is approximately 107 % at 1.6 GHz, making these devices very suitable as building blocks in many RF applications. 相似文献
5.
6.
Issam M. Kouatli 《Journal of Intelligent Manufacturing》1994,5(6):365-387
Applications of fuzzy control to industrial processes are mainly of multivariable structure. Using the traditional Zadeh principle would require a multidimensional relation to be developed representing a fuzzy model of the system. Such a multidimensional relation would result in memory overload to most industrial computers. Moreover, it would result in a highly complex compositional rule of inference to achieve the final output(s) of the system. This paper proposes a new simplified technique that avoids such complexity as well as memory overload for multivariable structure. Section 2 describes the proposed simplified multivariable technique to avoid memory overload. Section 3 demonstrates these techniques in the form of a robotic welding example where the objective is to control the speed of a robotic arm following an irregular path of weld. The speed value is dependent on the cavity size and determined by the cavity width and cavity depth as inputs. Section 4 describes an experimental application of the technique applied to an industrial process in the manufacture of force transducers termed as the cornering process. This application is composed of a two-inputs-two-outputs system. 相似文献
7.
CA Caldarone HK Najm M Kadletz JF Smallhorn RM Freedom WG Williams JG Coles 《Canadian Metallurgical Quarterly》1998,66(5):1521-1526
BACKGROUND: Recent reports have cited improving results for surgical management of isolated total anomalous pulmonary venous drainage. Complex cases (with other cardiac anomalies) are less frequently reported and are associated with higher mortality. METHODS: Retrospective review identified 170 consecutive patients treated for total anomalous pulmonary venous drainage from 1982 to 1996: 44 cases were "complex" (with significant associated cardiac lesions) and 126 cases were "simple." RESULTS: Operative mortality for simple cases decreased from 26% to 8%, and mortality for complex cases remained constant at 52%. Age, size, and the presence of atrial isomerism were univariate predictors of mortality. Multivariable analysis identified only univentricular hearts and associated cardiac lesions as predictors of operative mortality. Pulmonary artery (n = 16) and arteriopulmonary (n = 7) shunting strategies for complex cases resulted in less than 30% long-term survival. CONCLUSIONS: Despite improvement in survival for simple cases, management of total anomalous pulmonary venous drainage with single-ventricle hearts or other associated cardiac lesions remains problematic. 相似文献
8.
Carol Fung Jie Zhang Issam Aib Raouf Boutaba 《Journal of Network and Systems Management》2011,19(2):257-277
The accuracy of detecting an intrusion within a network of intrusion detection systems (IDSes) depends on the efficiency of
collaboration between member IDSes. The security itself within this network is an additional concern that needs to be addressed.
In this paper, we present a trust-based framework for secure and effective collaboration within an intrusion detection network
(IDN). In particular, we design a trust model that allows each IDS to evaluate the trustworthiness of other IDSes based on
its personal experience. We also propose an admission control algorithm for the IDS to manage the acquaintances it approaches
for advice about intrusions. We discuss the effectiveness of our approach in protecting the IDN against common attacks. Additionally,
experimental results demonstrate that our system yields significant improvement in detecting intrusions. The trust model further
improves the robustness of the collaborative system against malicious attacks. The experimental results also support that
our admission control algorithm is effective and fair, and creates incentives for collaboration. 相似文献
9.
In this work, the effects of the presence of surfactants in the liquid phase and the hydrodynamic regime of the bubble flow on the oxygen transfer rate were investigated in an electroflotation process in batch mode. The volumetric mass transfer coefficient KLα and the oxygenation capacity were evaluated to improve the performances of the electroflotation process in terms of oxygenation. In order to evaluate the liquid-side mass transfer coefficient KLα the volumetric mass transfer coefficient KLα was dissociated into KL and the specific interracial area (a) since the last one was obtained from the gas hold-up and the bubble diameter. The effect of Reynolds number which define the hydrodynamic of the bubble flow has been also studied. Models of KLa and KL have been established to show the effects of the hydrodynamic parameters and liquid phase characteristics on the oxygen transfer rate. 相似文献
10.