Groundwater Development in Arid Basins

Summary: Groundwater development frequently provides a means whereby tremendous new economic opportunities are opened up. If supplies are overdrawn (mined) the ensuing regional economy may be able to affort replacements from more costly sources. In the United States the Salt River Valley of Arizona and the valleys of California provide examples. Two cases are treated in this paper, Israel and West Pakistan. In Israel, besides furnishing more than half of the basic source of water suppply, groundwater development provides opportunity for both quantity and quality management, which makes possible use of surface supplies and reclaimed sewage as firm rather than marginal sources. This development will permit the total water resources of this small country, where agricultural production ranks among the world\u27s most efficient, to be utilized effectively down to almost the last drop by the mid 1970\u27s. Israel must then look to desalted water from the sea for further expansion of its overall water supply. In West Pakistan a combination of level terrain and leaky canals since about 1890 led to threatened waterlogging and salinity of more than 25 million acreas of irrigated land, even though supplies were less than half adequate for good productivity. By the 1950\u27s low yields and increasing population threatened starvation. However, initiation of groundwater development, first by the government and later by pricate entreprise, has, since 1960, let to construction of 3,500 governmental tube wells of about 3 cfs capacity and 30,000 private tube wells of slightly less than 1 cfs capacity. Results have been dramatic. Agricultural production and use of fertilizer are rapidly increasing, and opening of well development of pricate enterprise is providing the irrigator with benefits of free competition for his water custom which he did not previously enjoy. Ultimately, besides providing full supplies for an estimated 26 to 30 million acrea, drainage and salinity problems will be mitigated if about 50 million acre-feet are pumped each year from groundwater including about 28 million acre-feet to be mined from a reserve of about 1,900 million acre-feet. With some difficult surface storage development due to terrain, mining may eventually be reduced. Through an eventual technological solution for the continuing overdraft is not now in sight, perhaps an economy may be built which can affort such a solution when the time comes

The Role of Roles: Physical Cooperation between Humans and Robots

Since the strict separation of working spaces of humans and robots has experienced a softening due to recent robotics research achievements, close interaction of humans and robots comes rapidly into reach. In this context, physical human–robot interaction raises a number of questions regarding a desired intuitive robot behavior. The continuous bilateral information and energy exchange requires an appropriate continuous robot feedback. Investigating a cooperative manipulation task, the desired behavior is a combination of an urge to fulfill the task, a smooth instant reactive behavior to human force inputs and an assignment of the task effort to the cooperating agents. In this paper, a formal analysis of human–robot cooperative load transport is presented. Three different possibilities for the assignment of task effort are proposed. Two proposed dynamic role exchange mechanisms adjust the robot’s urge to complete the task based on the human feedback. For comparison, a static role allocation strategy not relying on the human agreement feedback is investigated as well. All three role allocation mechanisms are evaluated in a user study that involves large-scale kinesthetic interaction and full-body human motion. Results show tradeoffs between subjective and objective performance measures stating a clear objective advantage of the proposed dynamic role allocation scheme

Formation of organically surface-modified metal oxo clusters from carboxylic acids and metal alkoxides: a mechanistic study

The reaction of Zr(OR)4 (OR = OnBu, OnPr) with methacrylic acid was monitored by extended X-ray absorption fine structure (EXAFS), 1H and 13C NMR, HPLC, and Raman measurements. The study revealed that the initial dimeric zirconium alkoxides react rapidly with the carboxylic acid and form higher aggregated multinuclear compounds. EXAFS investigations showed that the structures of the resulting aggregates in solution depend on the carboxylic acid to alkoxide ratio. In addition, the reaction rates also differ depending on this ratio; while for a methacrylic acid to zirconium alkoxide ratio of 4 361 the reaction is slow, metal oxo clusters form rapidly with a 7 361 ratio. Methacrylic acid ester is simultaneously formed during the reaction, with concomitant production of water, required for the formation and condensation reactions in the cluster preparation

Perception of Spectral Changes in Multi-tone Complexes

Amplitude changes of the spectral components of a complex tone, relative to each other, are usually well perceived, even if the over-all intensity is kept fixed. Three experiments are reported: Experiment 1 dealt with the detectability of amplitude changes in two-tone complexes of fixed frequencies. Experiment 2 examined detection of slope changes in ramp-shaped spectral envelopes of two-and three-tone complexes as a function of spectral spacing. As a control experiment for some conditions a roving intensity level was used. Experiment 3 investigated the detectability of changes in the spectral slope of multi-tone complexes as a function of the number of components. The results of the experiments show that detection of spectral changes in a sound is strongly dependent on the frequency spacing of the components. It is concluded that the auditory system is capable of comparing the relative energy distributions over different critical bands. Within a critical band there exists an optimum frequency separation with respect to the detection of relative amplitude change