It's hip to be square : The CubeSat revolution

With the launch of the UK’s first commercial CubeSat, UKube-1, on the horizon, Malcolm Macdonald and Christopher Lowe look at what the future holds for this standardised spacecraft platform

Appendix B: Some morphometric parameters of named lakes with areas [greater than or equal to] 1.0 km2, and some smaller lakes, in New Zealand

Gaps indicate uncertainty or that accurate data are unavailable. Note that lakes with fluctuating levels e.g., those used for hydro-electric purposes, or near coasts have varying parameters. Table based mainly on Irwin (1975) with some data from Cunningham et al. (1953), Irwin (1972), Jolly & Brown (1975), Irwin & Pickrill (1983), Howard-Williams & Vincent 1984, Boswell et al. (1985), Livingstone et al. (1986), N.Z.O.I. Lake Chart series, N.Z. Topographical Map Series NZMS1 (1:63 360) and NZMS26O (1:50 000), and other sources

A summary of terminology used in tephra-related studies

The word ‘tephra’, derived from a Greek word for ash, is a collective term for all the unconsolidated, primary pyroclastic products of a volcanic eruption. We summarise here the meanings and applicability of this and related terms, including tephrostratigraphy, tephrochronology, tephrochronometry, tephrology, and cryptotephra. These and other tephra-based terms, some of which are erroneous or unnecessary, have been used in a wide range of stratigraphic and paleoenvironmental disciplines and in archaeology

Stratigraphy and development of c. 17 000 year old Lake Maratoto, North Island, New Zealand, with some inferences about postglacial climatic change

The stratigraphy and geomorphology of Lake Maratoto and its surrounds were investigated as part of a programme of paleolimnological studies based on sediment cores from lakes in northern North Island. Changes in the lake and catchment were inferred from variations in sediment character, the correlation and timing being determined from distinctive tephra layers in the sediments and by radiocarbon dating. Nineteen new C-l4 dates, on gyttja or peat, are reported (old T½, years B.P,): 11 on tephras (Mamaku Ash 6830 ±90. Wk227; Rotoma Ash 8370 ± 90, Wk522; 8350 ± 100, Wk523; Opepe Tephra 9370 ± 210, Wk230; Mangamate Tephra 9700 ± 140, Wk23l; 10000 ± 120, Wk232; Waiohau Ash 12 200 ± 230, Wk233; 12500 ± 190, Wk234; 12450 ± 200, Wk5l5; 12300 ± 190,Wk516; RotoruaAsh 13450 ± 120, Wk511); 5 on the deposition of Hinuera Formation alluvium (16 300 ± 250, Wk239; 16 900 ± 470, Wk240; 17050 ± 200, Wk358; 16200 +360 -340, Wk509; 15 850 ± 130, Wk510); and 3 on basal peat of the Rukuhia bog (10 250 ± 90, Wk114; 15200 ± 130, Wk534; 10600 ± 90, Wk553). Lake Maratoto originated c. 17 000 years ago when a small valley was dammed by volcanogenic alluvium (Hinuera Formation). From c. 17 000 to c. 14 000 years ago the lake was about 2 m deep with clear water. Marginal peat first developed at c. 15000 years ago, reducing the area of the lake by about one-half by c. 13 000 years ago. Lake area then expanded, possibly because of marginal erosion and/or oxidation of the peat, to its maximum size at the present day. The adjacent Rukuhia peat bog grew rapidly from c. 11 000 years ago and is now 8 m thick immediately to the west of the lake. As a result of this growth, the lake became dystrophic and deepened (3.5 m at c. 7000 years ago, 6.4 m at c. 2000 years ago, and 7. 1 m today). The developmental history suggests that net precipitation increased at c. 15 000 years ago, increased further at c. 11 000 years ago, remaining high to c. 7000 years ago at least, but with a decline at or before c. 2000 years ago. There may have been a distinctly wetter or windier period from c. 10 000 to 9000 years ago. This interpretation is consistent with other reconstructions of postglacial climate in the Southern Hemisphere

Lakes

Lakes have always held an aesthetic fascination for people; they figure prominently in both art and literature and have even been endowed with spiritual qualities. For example, the nineteenth century American writer Henry D. Thoreau (1854) considered a lake to be 'the landscape's most beautiful and expressive feature. It is the earth's eye; looking into which the beholder measures the depth of his own nature'. More prosaically, lakes are also of considerable geomorphological interest as dynamic landfonns originating in varied and often complex ways

Parametric CubeSat flight simulation architecture

This paper presents the architecture of a system of models that provides realistic simulation of the dynamic, in-orbit behaviour of a CubeSat. Time-dependent relationships between sub-systems and between the satellite and external nodes (ground stations and celestial bodies) are captured through numerical analysis of a multi-disciplinary set of state variables including position, attitude, stored energy, stored data and system temperature. Model-Based Systems Engineering and parametric modelling techniques are employed throughout to help visualise the models and ensure flexibility and expandability. Operational mode states are also incorporated within the design, allowing the systems engineer to assess flight behaviour over a range of mission scenarios. Finally, both long and short term dynamics are captured using a coupled-model philosophy; described as Lifetime and Operations models. An example mission is analysed and preliminary results are presented as an illustration of early capabilities

Through-life modelling of nano-satellite power system dynamics

This paper presents a multi-fidelity approach to finding optimal, mission-specific power system configurations for CubeSats. The methodology begins with propagation of the orbit elements over the mission lifetime, via a continuous-time model, accounting for orbital perturbations (drag, solar radiation and non-spherical geo-potential). Analytical sizing of the power system is then achieved at discrete long-term intervals, to account for the effects of variations in environmental conditions over the mission life. This sizing is based on worst case power demand and provides inputs to a numerical assessment of the in-flight energy collection for each potential solar array deployment configuration. Finally, two objective functions (minimum deviation about the orbit average power and maximum average power over the entire mission) are satisfied to identify the configurations most suitable for the specific mission requirement. Most Nano-satellites are designed with relatively simple, static-models only and tend to be over-engineered as a result, often leading to a power-limited system. The approach described here aims to reduce the uncertainty in energy collection during flight and provide a robust approach to finding the optimal solution for a given set of mission requirements

Plate waves for the NDT of diffusion bonded titanium.

Imperial Users onl

Observations upon appendicitis: based on an analysis of six hundred cases

The compulsory modification of the treatment of acute appendicitis to meet the requirements of a large industrial practice, far removed from hospital accommodation, enforced me to take a keen interest in the problem of this disease. Contrary to the teaching instilled in me during my undergraduate days, Iinstilled in me during my undergraduate days. I saw that many acute cases could be tided over without. operation. The fact that every case did not respond to non-operative regime raised the question: why do some resolve while others proceed to peritonitis?Since then, I have formulated a theory which has borne the test of time and which seems to solve many of the problems met with in the disease. This truth was forced upon me by special circumstances (1) in General Practice with no hospital accommodation -- medical treatment was largely adopted; (2) in General Practice with an attached hospital -- early diagnosis and early operation, if indicated; (3) in a General Hospital -- receiving cases where the disease was well established and many with general peritonitis.This truth explains, first, under what circwn- :stances cases treated medically will recover; second, why immediate operation gives good results; and third, the factor producing peritonitis.The Thesis presents the following : -(1) The chief factors influencing the position of the appendix, embryological and topographical; histological structure of the appendix; the abundance of lymphoid tissue; precarious blood supply and the communication vie lymph supply with stomach, duodenum and gall- bladder.(2) The functional importance of the appendix is considered from phylogenetic and structural grounds as well as from the effects of its removal. The conclusion arrived at is that we can believe that the appendix has a function yet it is essentially vesti- :gial in character and that its potentialities for harm are greater than its capability for good.(3) Aetiology is considered, appendicitis being due to a streptococcus borne via the blood stream from the teeth or tonsils. The appendix being a locus minoris resistentiae forms a nidus for those circulatory micro- organisms. Protein diet is an important predisposing factor.(4) The various pathological lesions are described from my own specimens and sections. Spread of the disease occurs(a) by contiguity of tissue to the peritoneum. (b) by blood stream to the liver. (c) by lymphatic stream to the stomach, duodenum and gall -bladder.The physiology of the peritoneum is considered and its powers of absorption and of forming adhesions lead in turn to toxic absorption and to intestinal obstruction if the infection spreads from the appendix to the peritoneal cavity.The means of limiting toxic absorption are discussed.(5) The symptoms of the condition are inflamaa- : tory or obstructive in or°iii. The value and si gn- :ificance of each symptom is assessed. and fallacies in their interpretation pointed out.The three outstanding symptoms are Pain which is of two types (i) initial or splanchnic (ii) secondary or due to involvement of the parietal peritoneum; Tenderness; and Rigidity.It is stressed that pain does not usually begin in the right iliac fossa.The severity of the symptoms can not be correlated with the severity of the pathological process.(6) Actual and differential diagnosis are considered and Murphy's triad-epigastric pain, vomiting, and pain in the right iliac fossa - emphasised. A warning against placing reliance on increase of temperature or a rapid pulse as positive evidence of acute appendicitis is given.The method of examination, importance of pelvic or rectal examination, are alluded to and the various' conditions from which appendicitis is to be differentiated are tabulated, special reference being made in the case of children and women,(7) The unsatisfactory condition of the diagnosis and treatment of chronic appendicitis is stressed and a Flea made for a more thorough clinical examination examination combined with an operative incision which will allow examination of other abdominal viscera.(6) The various factors concerned in prognosis are discussed, reduction of mortality being dependent upon prevention of peritonitis.As regards treatment, it is suggested that the whole key to the situation lies in the administration or withholding of an aperient.The Murphy-Ochsner treatment is feasible because purgation is prohibited. surgeons advise early operation before purgation has had time to act, i.e., before peritonitis has set in.These two methods of treatment have one common factor - a purgative.My experience is summed up in the statement: have yet to see a case of perforated appendicitis which has not had an aperient.Various authorities are quoted in support of the view that "the purge is more dangerous than the scalpel ".By early operation and by omission of a purgative, we are making doubly sure that peritonitis will not supervene; also early operation prevents the possibility of subsequent attacks.A short analysis of my series of 600 cases is given