January 31, 2005
16:05Z - Modifications completed
January 30, 2005
The first task is easy: the whole constitution can be found here (a page of the official site europa.eu.int) as a series of PDF files, one per chapter.
The synopsys and commentary will be a work-in-progress, but I can start with some considerations. First, this European Constitution is preposterously long: it totals more than 465 pages - although the juice is concentrated in the first 200(sic) or so. Probably for being a scientist/engineer, I prefer short and to the point documents. Those too long probably are either loaded with... manure or deal with issues that they should instead leave alone.
I think this constitutional draft falls in the second category: from the very beginning, it says that the EU must undertake certain policies and a certain stances - like sustainable development. I talks (or babbles) endlessly about values such a closer union, peaceful future and diversity. Then it proceeds to prohibit the death penalty, human cloning and sets "the prohibition on making the human body and its parts as such a source of financial gain" and so on.
I am not saying that alle of those values are certainly negative or something like that, but I do not think it's the role of a constitution to set such strict guidelines for the policies of a country. It may happen that a state needs to go to war, or resolve particular internal situations that require the use of force, for example. Not to mention The Will of The People, that should be the only source for the legitimacy of a government. While the underlying idea so popular among the European elites is that governments are self-legitimating.
I think I will proceed with my analysis in another post, because I feel like this one is getting confusing. Besides, I should read at least Part I and II of the constitution in a more organic manner.
The jihadis attacked and produced casualties, but nothing like the nightmare promise by Zarqawi. I am thinking that he made an empty threat, hoping to scare people, but his operational capabilities appear greatly impaired.
However, the always reliable BBC does not miss any occasion to give prominence to terror and violence, while the historical accomplishment of the vote sort of slips in the background:
But a spate of attacks hit Baghdad and surrounding areas in the hours after polls opened at 0700 (0400 GMT).
- At least three people died in an explosion on a bus reportedly carrying Sunni Arabs to a polling station south of Baghdad
- At least six people died when a bomber with explosives strapped to his body blew himself up outside a polling station in eastern Baghdad
- In western Baghdad, a suicide bomber killed at least four others and injured at least six people outside a polling station, and four policemen were reportedly killed in separate suicide attacks on polling stations
- In the capital's Sadr City district, at least four people died and seven were wounded when a mortar struck a polling station, and four other people were reported to have died in other attacks in or near the capital
- Explosions were also heard in Basra, Mosul and Baquba - where fighting is reported to have broken out in the south of the city
- One guard died in an apparent assassination attempt on the interim justice minister, who was untouched.
Despite the attacks in Baghdad, voting at polling stations in the country's mostly Shia Muslim south and Kurdish north was said to be brisk.Yes you can always rely on BBC for defeatism, depicting the glass as half-empty and what looks suspiciously like pro-jihad propaganda.
I have no illusions that Iraq will become a paradise overnight. There are still big problems to tackle, mainly the pervasive influence of Islam and Arabic tribalism - which aren't really compatible with a modern democracy.
However, these elections were an indispensable first step on the long road to freedom and democracy.
Stand fast, be brave and good luck Iraq!
Update 21:45Z: I knew that the moonbats weren't very excited for the Iraqi elections, but these moonbats in Spain go far over the top and protest explicitly against the vote. And they say they stand for democracy. Yeah, sure. Compare and contrast the spanish left, that voted for appeasement after the (horrific) Madrid bombing, and the Iraqis who went to vote despite the months of terror and bombs, and the attacks to the polling stations (there are reports of voters who actually taunted eventual jihadis, go figure). Who's braver?
January 29, 2005
But there are other consequences. In my opinion, a very important one is that if we try to describe a system with the wrong model, we will obtain incorrect predictions. And one mistake I see being made very often is oversemplification. This often appears as thinking that there is one or a few "root causes" that can explain almost everything.
I have a different point of view. I think that every society-wide behaviour can be explained only recurring to a number of causes and factors each with different importance. There are main causes, and secondary ones. There are factors almost universal for any man in the world, and others which are local and particular. Thus, when someone says "If we do X, the consequence will be Y", I tend to distrust. Probably the reaction will be Y, but exactly to what degree it's hard to say. Or together with Y, also and undesidered Z may occur. And so on.
That also explains why I do not easily label people or societies as evil: sometimes, a behaviour causing horrible consequences is the result of mistakes (incorrect system analysis), not of evil intentions. But evil people and evil ideologies do exist, I'm sure of that.
These considerations are not an argument for moral relativism as expressed by the old saying "The world is not black and white, but rather a greyscale". Instead, reality is complex, a different concept. I drew my conclusions from this realization; feel free to draw yours.
Update 31/01/05: Wretchard himself has similar views.
[...]I might be wrong, but large scale, historical phenomena are rarely explicable by little formulas of the sort Hersh was talking about, because complex systems are often nonlinear, emergent, etc. For that reason, these 'secret of the universe' confidences often sound a little odd, i.e. the 'Philadelpha Experiment really happened', 'the US Government secretly has the Ark of the Covenant', etc. That's not to say they are never true. Occasionally there is a simple explanation for everything and they are out to get you.[...]
No, he wasn't engaged in a discussion with me, if you ask.
January 28, 2005
The student, D. H., who is in the fourth year of a mechanical engineering degree, was crossing Prince Consort Road on Tuesday lunchtime when he was hit by the car. He was unhurt. The driver of the taxi blamed Mr Houcke for the collision and attempted to place him under a citizen’s arrest. Police were called to the scene, where they questioned the two men but took no further action.
January 27, 2005
Reality can be described as a number of complex systems, which interact with each other. Systems are objects, mechanical devices, computers, airplanes. But also living cells and higher beings are systems, as groups of people are. Also corporations and markets are systems, together with the atmosphere and lands.
The degree of complexity of all these systems is very variable: it can go from trivial to inextricable. But there are common aspects between all systems: they are consituted of components (which can be sub-systems in their turn) which interact with each other, and often also communicate with each other.
It's the patterns of interaction and communication that vary wildly, in quality and quantity. In a chemical plant (which are fairly complex systems), there are hundreds of components - thermometers, pressure sensors, flow and level sensors, heaters/coolers, pumps, valves, pressure regulators, reactors, distillation columns, flow regulators - just to cite the main ones. The communications between all these components pass through electrical signals (more recently, optic fibers) going from the sensors to elaborators which first correlate the signal from the instrument to a numerical value, display it to the human operators, then confront this value with a set point and/or measurements from other instruments and finally, if needed, send signals to actuators that will open or close valves, give more or less power to heaters, all in order to keep the process variables within the design limits - all this in the interested of quality and safety. This is a regulation mechanism. In many systems, like jetliners, certain operations cannot be performed if certain conditions are not met, because it would jeopardize safety. For example, commercial planes cannot deploy flaps at cruise speed because it would destabilize the plane.
But an Airbus A380 is a trivial system compared to even a simple animal, like a fly. Its components are cells, and objects smaller than cells. There are billions of them, and they communicate all the time, with each other, through hundreds chemical messengers and receptors. All these mechanisms are only in part clear. But probably the most complex system in existence is the human brain, with its staggering number of neurons and ever-astounding capabilities. We know only very little of how a human brain really works, actually.
Systems can be described with mathematical models (models are not necessarily mathemathical; they can also be pictorial... you get the idea, I hope), but these models tend to become quickly difficult and cumbersome. Sometimes we don't know how to write the pertinent equations, and even when can do that, it is possible that there is not enough computational power available to resolve them. So, when facing the task of describing a system, scientists and engineers begin with a simple model, as simple as possible, taking into account only the major factors and features of the system. Then the results of this model are compared with experimental observations, and the model is modified to take into account minor factors and subtler features. The process is repeated until the predictions of the model become sufficiently accurate. What "sufficiently accurate" means, varies greatly from case to case - and from the resources you can use in the modelling phase. It can go from a rough approximation to numbers exact to the sixth decimal place. If the structure of the system is not known well, or it is impossible to measure properly the input and output variables, the resulting model will be poor.
As a general rule, the more complex is a system, the more difficult will be to develop a sufficiently accurate mathematical model. We want a model in order to design systems that can succesfully perform a certain task, but also to improve the performance of existing ones and to predict how certain systems will react to perturbations and changes in their operational environment. Mathematical modelling also can uncover similarities and analogies between apparently different systems, and that is of extreme importance.
Some systems reach a steady state (that's what chemical engineers strive for, when designing their plants), while others tend to oscillate around an equilibrium position. It's an uncomfortable situation, but it happens. Some ecosystems follow this trend, and I strongly suspect that also free markets fall in the same category: phases of boom and bust are an inherent features of them.
The extreme case is a chaotic system, one for which we are unble to predict with any useful accuracy its reactions to a perturbation or environmental changes (this is a pragmatic definition of a chaotic system). Steven DenBeste, who is a system engineer himself, wrote quite a few times about complex and chaotic systems.
Regulation mechanism often manifest as feedback loops, which can be negative or positive (feedforward loops exist, too), and the feedback amplitude is different from system to system, from cycle to cycle. In some cases, it even is non-linear. An example of negative feedback are smart" temperature controllers, that reduce the heating power when a furnace is near its set temperature. On the other hand, there are level controllers that can increase the flow out of a tank when the liquid level increases: positive feedback. Feedback loops can be interlocked, meaning that one influences another.
Systems also show latency, that is a time delay between the perturbation and the reaction: latency can be tricky, because while we wait for a perturbation to cause an effect, another change with a shorter latency time may occur and thus the response we observe is caused by the superimposition of two different perturbations.
The last feature is hysteresis. This is a bit more difficult to explain: we apply a perturbation to a system, and we that the system responds in a certain way and a certain time. Then we remove the perturbation, and we notice that the system returns to its initial state following a different path, more slowly or faster than in the first case. Certain perturbations may even cause permanent changes. This is hysteresis.
But what are the practical, everyday, implications of all this, you may ask?
Well, for now my time is over. Soon I will draw conclusions from my exposition of complex systems.
January 24, 2005
Al termine del processo, il giudice Forleo riconosce che gli imputati "avevano come precipuo scopo il finanziamento, e più in generale il sostegno di strutture di addestramento paramilitare site in zone mediorientali, presumibilmente stanziate nel nord dell'Iraq". E anche che, a tal scopo " erano organizzati sia la raccolta e l'invio di somme di denaro, sia l'arruolamento di volontari, tutti stranieri e tutti di matrice islamico-fondamentalista". Ma "non risulta invece provato - aggiunge il giudice - che tali strutture paramilitari prevedessero la concreta programmazione di obiettivi trascendenti attività di guerriglia da innescare in detti (cioè in Iraq, ndr) o in altri prevedibili contesti bellici, e dunque incasellabili nell'ambito delle attività di tipo terroristico".
Niente attivitá teroristiche, eh? E quegli attentati che in Iraq uccidono decine di civili un giorno sí e l'altro pure, cosa sono? O forse Forleo ritiene legittimi attentati come quello di Nassiriya, che é costato la vita ad una ventina fra soldati e carabinieri italiani?
Questa non é una questione di ordine pubblico; é una guerra globale contro l'Islamismo, quando verrá finalmente compreso? Non ho parole accettabili per esprimere quello che penso di questo giudice. Vergogna e disonore su tutti quelli come lui. (Precisazione: gli imputati erano accusati di avere finanziato la jihad e reclutato combattenti in preparazione all'operazione OIF).
"Non dubito della preparazione giuridica del Gup - prosegue il vicepremier - ma distinguere in Iraq 'attività di guerriglia da 'attività di tipo terroristico' e scrivere che è 'notorio che nel conflitto bellico in questione strumenti di altissima potenzialità offensiva sono stati innescati da tutte le forze in campo', significa mettere sullo stesso piano vittime e carnefici".
Calderoli (Ministro delle Riforme) pure:
I nostri poveri diciannove connazionali dilaniati dall'autobomba a Nassiriya, e le altre migliaia di persone uccise barbaramente dai kamikaze in nome di un dio crudele ed assassino, sarebbero forse morti per azioni di guerriglia? Consiglio al giudice Forleo di guardarsi sui siti internet tutte le decapitazioni e gli sgozzamenti".
Cento, dei Verdi, invece costituisce un ottimo esemplare di idiotariano:
[...]non è la prima volta che azioni di repressione nei confronti di cittadini islamici si risolvono in una bolla di sapone perché mancano i requisiti previsti dal Codice Penale e dalla Costituzione. Le motivazioni della sentenza, a una prima lettura, appaiono, infatti, ineccepibili".
Non é che mancano i requisiti; é che un giudice ha usato una distinzione fra terrorismo e guerriglia che non ha alcuna relazione con la situazione in Iraq e della Jihad piú in generale, capito?
Non molti lo capiscono, invece. L'editorialista Giuseppe D'Avanzo sulla Repubblica ricade nelle solite trappole: ritiene che la jihad globale sia una mera questione di ordine pubblico - quindi da trattare con tutte le regole e le garanzie per gli jihadisti che sono riservate ai criminali comuni. Ed anche ritiene valide quelle definizioni di terrorismo che si basano sulla violenza verso i non-combattenti: mentre queste definizioni hanno un fondo di veritá, sono troppo vaghe e larghe per essere veramente utili in pratica.
Nessun commento ancora sul giornale conservatore Il Foglio, che peró riporta la notizia di una imponente manifestazione a Mogadiscio per protestare la distruzione del cimitero italiano avvenuta pochi giorni fa.
For my english readers: I'll try to prepare an English version of this post too. For the time being, Mistery Achievement has it.
January 23, 2005
Guardate cosa dice in merito al-Zarqawi in persona:
La voce - che il sito identifica con quella di Zarqawi - dice testualmente: "Abbiamo dichiarato una guerra dura contro il principio della democrazia e tutti coloro che vogliono metterla in atto. I candidati alle elezioni stanno tentando di diventare semidei mentre coloro che votano per loro sono infedeli. E Dio mi è testimone, io li ho informati (delle nostre intenzioni)".
La traduzione potrebbe non essere totalmente accurata, ma queste parole is commentano da sole: "guerra dura contro il principio della democrazia e tutti coloro che vogliono metterla in atto".
Come sia possibile che qualcuno non abbia ancora capito da che parte stanno gli jihadisti, è un mistero insondabile per me.
A questo punto, è di fondamentale importanza che le elezioni in Iraq si svolgano come programmato anche se la "situazione della sicurezza" è lontana dalla perfezione. L'obbiettivo degli jihadisti è di impedire o quantomeno ritardare le elezioni.
January 22, 2005
The main obstacle is that hydrogen and methanol are still much more expensive than conventional hydrocarbon fuels, both in terms of money and energy spent to produce them. To lower the cost of these fuels to competitive levels, better processes of desulphurization, reforming and purification are required. These are quite specific subjects, and I'm afraid that people without at least a good knowledge of chemistry (chemical engineering even better) cannot fully understand why it's difficult and time-consuming to obtain significant progresses in these fields. But take my word for it, even if researchers have money and work hard, sometimes results take a long time to come out.
Professor Song and his group, hovewer, last year proposed an almost revolutionary approach to the desulphurization of hydrocarbon fuels: the sulphur-containing compounds are adsorbed on specifically designed materials and thus separated from the rest of the fuel, to be eventually hydrogenated later. In this way, only a small fraction of the original fuel stream needs to be treated with hydrogen, and this can bring significant savings.
However, it's common opinion among the experts in the field that fuel-cell powered cars are not such a big deal. Yes, the media love them, but the best applications of fuel cells are others.
* At a certain point, Song showed a slide with a pic of President Bush, and his State of the Union speech when he decided to devote $1.7 billions to an alterantive fuels research programs. I could feel the horror emanating from some mebers of the audience: "The Idiot Evilgenius Chimpy BusHitler is only a puppet of the evil Halliburton Military-Industrial Complex conspiracyl... how can he have a good idea? He can not, he must not!" they were probably thinking.
And now, The Experiment.
I decided to experimentally activate comments on my blog.
I am not a patient guy, and the amount of time I can dedicate to blogging is limited, so comments will be restricted to registered Blogger users - and I will be ruthless against eventual trolls and other obnoxious types. Lunatic ravings, anti-American and anti-Jew rants will probably cause immediate banning and deletion, together with anti-Arab and anti-European ones.
Remember, this blog is my own little piece of cyberspace of which I am lord & tyrant.
Of course, comments do not necessarily reflect my views and opinions.
January 21, 2005
I am I bit puzzled by these editorial choices, so I looked up some of these words, trying to understand their use.
While militant apparently has quite a warrying meaning (although its common use is different), activist has a markedly different connotation - of someone maybe not totally peaceful, but not intent on waging a shooting war. Not to mention gunman, that refers much more to common criminals than to politically-motivated fighters.
So, of the terms described above, activists and gunmen look to me way off target, while all the rest are quite accurate. Terrorists is banned because considered an exceedingly loaded and judgemental term. But for me, terrorists are those who adhere to the military doctrine of terrorism - and guerrillas adhere to the doctrine of guerrilla.
Instead, terrorists is too often used as an epiteth to indicate "very bad guys who kill civilians". This is not an useful definition.
Thus it happened that a terrorist is seen as morally worse than a rebel, insurgent or a generic fighter, while it may not necessarily be the same - or better, the real distinction lies more in the objectives than in the doctrine employed. With some limits, of course: we in the West righteously tend to minimize collateral damage no matter what.
But the real reason for Reuters et al. not to use "loaded" words is not to upset some parties, mainly the same fighters (let's go with this term, for now) mentioned in the article. This happens because many of these news outlets rely heavily on local sources (partly for ideological similarities, partly for mere convenience - the whole thing is rather complex), and upsetting them would mean the end of a situation that is good for both the media and the fighters: the media have an endless stream of news, often very spectacular and emotionally-loaded, while the fighters get the acritic and widespread propaganda they want and need. Not to mention physical risk for some reporters.
The situation is complicated by the fact that those fighters do different things at the same time: thee are rebelling against the Iraqi government, they are engaged in both terrorism and guerrilla, and other things.
So what's the correct term? I propose jihadis.
Because that's what they are doing: fighting jihad, the Holy War against the Infidels mandated by the Quran (or at least by the mainstream interpretations of this book) and preached as a duty for any "good" muslim. Any available means, doctrine and strategies are considered legitimate to fight the jihad, and jihadis have a thing for beheadings and other gruesome forms of killing - which in this age of fast information are abundantly displayed in pictures and videos for propaganda use.
And maybe this term would not even upset the jihadis so much, because they are proud of fighting jihad...
January 20, 2005
I momenti di stabilitá climatica sono brevi ed effimeri, poco piú di attimi fuggenti sulla scala degli eventi geologici ed evolutivi.
Comunque, supponiamo di volere misurare la variazione di temperatura della Terra in questi ultimi anni, e tentare di stabilire se é troppo veloce per essere considerata naturale.
Per prima cosa, é necessario stabilire una linea di base, ovvero una sorta di media, di valore "normale" rispetto al quale misurare i cambiamenti. Quali dati possiamo usare per determinare la linea di base?
Le temperature rilevate su tutta la Terra, o solo parte di essa? Regioni polari od equatoriali? Aree urbane o rurali? Le temperature nelle aree urbane sono generalmente piú alte a causa dell'effetto cittá. Usiamo le temperature misurate al suolo, oppure quelle dell'alta atmosfera, o quelle della superficie marina? Le temperature estive, invernali, o una media annuale?
Ed ancora, su quale periodo calcoliamo la linea di base? Gli ultimi 10 anni, gli ultimi 20, 50, 100? In genere, andando indietro nel tempo la quantita di dati disponibili é minore, cosí come la loro qualitá. Cosa fare poi in caso di dati mancanti o di qualitá troppo scadente?
Molte delle alternative possibili sono egualmente legittime, ma chi scrive articoli deve accertarsi per prima cosa di usare dati consistenti (non si puó confrontare direttamente la variazione delle temperature estive con la variazione delle temperature invernali, ad esempio), e quindi deve spiegare chiaramente quali scelte sono state fatte e per quali motivi, cosí che altri scienziati possano verificare (o invalidare) le conclusioni raggiunte.
Comunque, tutte queste situazioni finiscono per produrre un margine di errore piuttosto rilevante per quanto riguarda la linea di base. Quando ci accingiamo a misurare le variazioni di temperatura, ci troviamo di fronte agli stessi problemi, ed infine otteniamo di nuovo dati con un certo margine di errore.
Chi sostiene l'origine antropica del cambiamento climatico usa come prova il fatto che, apparentemente, la temperatura media della superficie terrestre é cresciuta molto piú velocemente dall'inizio dell'era industriale di quanti sia stato mai misurato in precedenza.
Tuttavia, io vedo almeno un paio di fallacie in questo ragionamento: uno, per le ragioni che ho esposto, la pendenza del grafico della temperatura non mi sembra un paramentro particolarmente affidabile. Due, altre ricerche sembrano dimostrare che pure in epoca pre-industriale (ed anche preistorica) ci sono stati veloci cambiamente climatici.
Se poi l'andamento delle temperature nel recente passato viene utilizzato per fare previsioni riguardo al futuro, si entra in un campo quasi esoterico: é ben noto in statistica che l'incertezza delle estrapolazioni é molto grande - e quindi i risultati cosí ottenuti poco affidabili.
Comunque, supponiamo di avere fatto un lavoro accurato, e di avere dimostrato che durante l'ultimo secolo l'aumento della temperatura é stato cosí veloce da risultare sospetto come fenomento naturale. Inoltre, dall'era preindustriale la concentrazione di anidride carbonica nell'atmosfera é cresciuta del 30%.
Qualcuno prende questi fatti come prova che il "riscaldamento globale" sia causato dall'anidride carbonica di origine antropica.
Invece, quello che esiste é al massimo una correlazione - due fatti sono che avvengono contemporaneamente od a breve tempo uno dall'altro. Ma per dimostrare l'esistenza di un legame di causalitá serve molto di piú.
Ci sarebbero molte altre considerazioni di fare - se questo riscaldamento causi fenomeni meteo piú violenti oppure no, se alla fine sia davvero un male (le gelide distese di Canada e Siberia diventerebbero fertili zone temperate, in certi scenari...), se sia meglio tentare di evitare il cambiamento climatico oppure adattarsi... ma il punto fondamentale é che la nostra conoscenza dei meccanismi che regolano il clima é ancora scarsa e superficiale.
Molti scienziati ritengono che l'effetto dell'anidride carbonica sulla temperatura della Terra sia decisamente secondario, mentre il clima é principalmente regolato da fattori terrestri ed astronomici che sono totalmente al di fuori del nostro controllo ed influenza.
Quindi c'é davvero bisogno di sollevare un tale polverone in merito al Protocollo di Kyoto?
Tech Central Station ha un'intera sezione sul cambiamento climatico.
January 19, 2005
Well, read about this movie, then this story and draw your conclusions...
January 16, 2005
Say welcome to Jinnderella and her Hot Needle of Inquiry: I followed her steps since her days as a commenter on LGF, and found her intellectually attractive. Physically, who knows?
And halso greeting to Rishon-Rishon. Its owner David lives in Israel, and he's not the usual amateur pundit who spends half of his time bitching about how evil the Palestinians are. No, he's cut from a different, and more interesting fabric.
Update 21/1/05: Jinnderella is also good looking!
January 15, 2005
The whole Cassini mission already produced interesting data, such as high-resolution pictures of Saturn's awesome rings system (someone called Saturn "The Lord of the Rings"), but the landing on Titan is an outstanding accomplishment- of both NASA and ESA, it would be stupid and childish to say that one was more important than the other.
The first pictures of Titan's surface show something very interesting: there are drainage channels, and lakes or seas. This means that there are liquids, flowing, that Titan is a "live" satellite.
The surface temperature is so low that water can be found only as ice, and the liquids are probably hydrocarbons, but it's already a more favorable environment than the cold, arid Martian deserts, or the scorching hot surface of Venus. From what I've heard on TV last night, pre-biotic molecules were detected in Titan's atmosphere too.
However, the mission did not go perfectly: one of Huygens' two communication channels malfunctioned, and this reduced the amount of data that were transmitted to Cassini and then to Earth. But I regard this only as a minor glitch: Cassini and Huygens travelled many million kilometers for seven years, and a lot of things may have gone wrong during all that time. But it did not happen. While in recent years other missions ended with spectacular failures: two probes crashed onto Mars, and the capsule carrying back a comet's materials did not deploy its parachute and crashed in the Nevada desert - making the whole mission almost useless.
So three cheers for Cassini and Huygens, for NASA and ESA, for all the men and women (and transgenders and transvestites, eh...) who made all this possible with their ingenuity and dedication!
January 13, 2005
Actually, the number of nuclear accidents is very low, but they can be very serious - although only chernobyl had a wide impact on people and environment. But that was enough for the general public to see nuclear energy as a barely tolerable risk.
Yes, reactors can be made safer, and more containment structures can greatly mitigate the consequences of core damage. But adding layers of safety makes things more complicated, and enormously more expensive. The big and thick steel pressure vessels that encase the reactor cores cost many million dollars alone. Thus, nuclear power stations are often not economically viable, because they will not produce cheap energy.
A different basic design is needed to address those issues altogether.
So we come to the pellet bed reactor. The idea is not really new - the first reactor of this kind was proposed in the USA in the '40s by Farrington Daniels, but then rod-fueled and water-cooled reactors were preferred - not really for technical reasons.
In this kind of nuclear reactor, the fuel is in form of small balls arranged in a bed (much like a fixed-bed chemical reactor) with gaseous helium passing through the bed to carry heat away. The use of helium alone resolves many problems, because helium is chemically inert and a quasi-ideal gas. On the other hand, high-pressure steam and superheated water are corrosive and at high temperature can react chemically with the fuel or rod materials (generally, zirconium).
The pebble-bed reactor was studied by different groups, but no-one came up with a commercially viable design. Until a few years ago, when a Chinese research group (with considerable help from German groups and companies) activated a 10 MW experimental unit, named HTR-10 (high temperature reactor, 10 MW). Not casually this reactor was developed in China: the rapid Chinese development requires huge amounts of electricity, and China is devoting great resources to research and development in many fields. Wired has a good divulgative article, but a much more in-depth description of the reactor is in the monographic Volume 218 of Nuclear Engineering and Design, October 2002. And now don't tell me that your barber shop does not have Nuclear Engineering and Design!
In this reactor, the fuel is uranium oxide-loaded graphite balls, 6 cm in diameter and containing 5 g of enriched uranium each, that move slowly down a properly designed chamber, lined with graphite bricks to reflect back neutrons, and then boronated carbon bricks for thermal insulation and radiation shielding. The coolant is gaseous helium at about 3.0 MPa, which enters the core at 250 C and exits at about 700 C, while the fuel balls will reach the maximum temperature of 800 - 870 C during normal operation. The hot helium then is routed to a heat exchanger in onrder to produce steam to drive the turbine, and circulated back to the core by a blower. There are 10 control rods to control the fission and eventually shut down the reactor, plus containers filled with neutron-absorbing balls ready to be discharged in the core if emergency shutdown is required.
The fuel balls exit one by one at the bottom of the reactor, and they are automatically examined to discard the damaged and burnt-up ones while those still suitable are reloaded at the top.
In case of accident and cooling failure, the fission and decay heat will be dissipated through the reactor walls in the housing cavity, and then to the outside by oversized natural-circulation water coolers. But even in the case of failure of these coolers, the reactor is designed in such a way that the fuel elements will not exceed the safe temperature of 1600 C (a maximum of 1033 C is estimated in case of accident). That's the main feature of the HTR, indeed: even with no core cooling, the temperature of fuel elements will not excedd safe limits and that depends from geometric and physical factors, not intervention of automatic or manual safety systems. Another, subtler, safety mechanism is the so-called "negative reactivity temperature coefficient": for reasons quite difficult to explain, in this kind of reactors the fission rate decreases when the temperature of the fuel increases, thus generating less heat.
If a conventional water-cooled reactor loses its cooling, damage to fuel rods is very likely (it depends wether the reactor is shut down quickly enough or not). There may be no radiactivity dispersion, but it's not a comfortable situation anyway.
The fuel elements itself are very safe: they contain low enriched uranium as spherical particles of uranium oxide coated with a multi-layer coating of pyrolitic carbon (similar to graphite) and silicon carbide: this coating has the function of containing the fission products (which are mainly solids and gases) up to 1600 C. These coated particles are subsequently mixed with graphite and pressed in a ball with a 10 mm uranium-free layer at its periphery (The process is actually very complex, and likely to be rather expensive). The fraction of free uranium (uranium out of the coating) is very low, no more than 0.01% of the total. This means that only a minimal amount of fission products will be released in the cooling helium. Given that graphite, pyrolitic carbon and silicon carbide all have high corrosion resistance, the spent fuel balls pose a less serious disposal problem than spent fuel from conventional reactors. In fact, spent rods are first left to cool down in a water basin, and after some steps of processing, the radiaoctive waste is disposed of in special containers, but even the best containers will be corroded after a few hundred years - that's why radioactive waste dumps need to be placed in stable and dry geological formations, because water accelerates corrosion and carries away the radioactive elements. I don't know exactly the corrosion rate of graphite and SiC, but my guess is that these materials will happily last many thousand years.
At a first glance, the HTR seems also a scarcely efficient system to produce plutonium for weapons use, and that's a factor to consider.
China is expecting to build many Modular HTR units, beginning from 2006 with a demonstrative plant, in order to reduce the consumption of fossil fuels and produce cheap and abundant electricity. Different turbine options are being evaluated, the most interesting one being the direct helium turbine and steam turbine cycle: with this design, hot helium is directly passed into a gas turbine, and the residual heat in the effluent used to produce steam before helium is returned to the reactor's core. This solution is very efficient, but it would require re-design and re-testing of many parts of the reactor.
Research and development is underway, both for the HTR-Module and to improve the fuel production process.
Also Western research groups are studying HTRs, because electricity production is not only a Chinese issue.
The real problem - not in China but in the power-hungry West - is to make the public accept this kind of reactors. The Chinese group trusts the fact that the safety concept of the HTR is easier to understand even for people without engineering knowledge, but I am afraid that it will be rather difficult - especially in Europe where the enviro-folks are ready to rattle the Chernobyl spectre everytime anything nuclear is mentioned. Time will tell, but for my part I would be glad to see HTRs being built.
January 12, 2005
[...]Quella famiglia di senegalesi che, ieri mattina, hanno trovato l'auto devastata dalla vernice e quella frase assurda a sporcare il muro di fronte a casa: « via i neri ».
A parte l'infamia del gesto, c'é una cosa che mi ha colpito: la parola usata é "neri", un termine abbastanza politicamente corretto. Non il piú dispregiativo "negri" o qualcosa del genere.
Per cui mi chiedo, é piú razzista chi scrive "Via i neri", oppure chi usa il termine "negri" senza peró nutrire una reale animositá verso le "persone di colore"?
E' sufficiente imporre codici di linguaggio per eradicare il razzismo? (No)
Conta piú la forma - quali parole vengono usate, o la sostanza - quello che uno veramente pensa e fa?
Io ritengo che, alla fine dei conti, la sostanza sia molto piú importante della forma, e la dottrina del politicamente corretto é in gran parte un cumulo di spazzatura, visto che si occupa principalmente della forma.
January 11, 2005
All traditional signals and barriers used to separate the carriageway and pavement will be removed and the question of who has priority will deliberately be left open. Even the kerb will be eliminated as part of the scheme to create Britain’s first such “shared space”. (From The Times)
Given that Exhibition Road is a couple of minutes away from my workplace, I think I'll keep a watch, and keep you informed on this experiment.
On Tue 11 Jan 2005 the status of Exhibition Road is: no roadworks in sight. The road was resurfaced just a few months ago.
January 10, 2005
I may look very skeptical on alternative energy sources, but it's not really true. I just want to moderate the excessive enthusiasm of some people about alternative energy, and the most misunderstood idea of these days, that is the "Hydrogen Economy".
Hydrogen is a highly flammable gas, lighter than air. In the reasearch and industrial environment, people are righteously wary of hydrogen: its use is dangerous, and maximum attention is required to avoid serious accidents. Hydrogen molecules are very small, and that means that hydrogen will escape from the tiniest holes and cracks in a tank or line.
The flammability of hydrogen was one of the causes of the Hindenburg airship tragedy. There is also another tricky issue about hydrogen: usually, if a compressed gas expands through a small orifice (like a leak from a line, or a punctured vessel), its temperature will decrease. But not hydrogen: this gas, and helium, will instead heat up upon expansion (it depends from their molecular properties) and eventually reach the auto-ignition temperature, thus causing a fire or even an explosion. The widespread use of hydrogen as a fuel (especially for automobiles) poses serious safety problems. Cars would explode in case of accident like you see in bad action movies, and refilling stations need special features to ensure safety. I think hydrogen may be suitable for trains, buses, ships, this sort of larger vehicles with a lower risk of accident.
Not to mention the fact that there are no distribution and refilling structure and facilities for hydrogen, and while they can be built, it will take at least several years and a lot of money - if the NIMBY sindrome does not kick in.
But the crux of the issue is that hydrogen is not an energy source, but just a fuel. It is less polluting (and potentially more efficient) than hydrocarbons, but it still has the same function, that is moving chemical energy from one place to another. There are no natural sources of hydrogen, apart from a small concentration in natural gas. Hydrogen must be produced, and the most efficient way is to react steam with a carbon-containing fuel (gas, oil, coal, biomass etc) in a steam reformer. With this process, we obtain hydrogen but also carbon dioxide, plus ashes if coal or biomass are used as fuel, and the problem of carbon dioxide emissions is not resolved - if such a problem is really so serious, something that we do not know yet. However, this process has the benefit of reducing the diffuse pollution from vehicles, which will emit only water vapour (maybe a little of nitrogen oxides). The steam reforming plants will be only a few, localized and easier to control and run properly. The overall pollution will probably be reduced this way, but at a considerable cost.
Another way to produce hydrogen is water electrolysis, but it needs huge amounts of electricity, and thus we return to the problems of energy production. A vision is a photovoltaic cell farm used to electrolize water, but such a process may very well be too inefficient to be of any interest. Nucular energy will not be appreciated by many enviro-folks, who instead crazily love hydrogen. Other systems have been proposed, from photoelectrolysis (a cell that will electrolize water simply exposing it to sunlight in presence of an appropriate catalyst) to hydrogen-producing bacteria, but none of them is commercially available now (things may change, however).
There are huge scientific and enegineering problems to solve before hydrogen will become a fuel of widespread use, and my take is that it will remain too dangerous to be used in cars.
Still, I think that alternative energy sources have a good potential, especially for developing and under-developed areas, where something like a 300 W water turbine can make the difference between some electricity and none at all. See, we in the West are used to have plenty of electricity at our disposal, but in a place where people still use oil lamps, a sinlge electrical lightbulb makes a big difference. But the for the bulk of electricity production in developed countries, I think we'll have to rely on conventional sources for many more years.
January 08, 2005
On the serious side, Belmont Club and Silent Running (among several others) are angaged in a debate over what can be considered torture - and more to the point, what is admissible in order to extract important information from enemy prisoners. Because the core of the issue is that, if we are too nice with them, we will be damaged. And the sufference of some of them will avoid the sufference of eventually many of us.
This is also related to thoughts that are haunting my mind from some time: it's about the complexity of reality that pervades every aspect. Sytems are complex, human behaviour is inetricably complex... and there are acts posing difficult ethical questions.
I am wary of anyone, from left or right, trying to oversemplify reality, trying to give absolute answers to those ethical questions.
January 02, 2005
The only real drawback in this pitiful dial-up connection, even more aggravated by a coal-powered P200 with 64 MB Ram and Win98... it's almost archeology, I know.
But soon I'll be back in activity as usual, stay tuned!
And a happy and fulfilling 2005 to my readers!